JP2004347134A - Complex heat exchanger tube and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a complex heat exchanger tube superior in heat transfer performance, bending workability, pressure resisting strength and productivity and helpful for smaller and lighter equipment to be used, and its manufacturing method. <P>SOLUTION: The complex heat exchanger tube 1 comprises an large-diameter tube 2 having three or four grooved portions 4 formed in at least part of an outer surface excluding both ends 2a, 2b in parallel to the direction of the tube axis and three or four small-diameter tubes 3 each having a diameter smaller than the diameter of the large-diameter tube 2 and fitted to the three or four grooved portions 4, respectively. The surface of the grooved portion 4 adjacent to the small-diameter tube 3 has a circular arc equal to that of the small-diameter tube 3 contacting the surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０１３９】
【表２】

【０１４０】
【表３】

【０１４１】
（３）評価結果
実施例１は、他の実施例２〜６よりｔ／Ｔが小さく、大径管に形成された溝部が深くなったため、嵌合により小径管にかぶさった大径管の突起部４ａ、４ａ（図１１参照）が長く、この部分の密着状況は良好であった。そして、溝底部分４ｂ、４ｂ、４ｂ（図２参照）に相当する位置に隙間が形成されたが、その隙間は大きいものでなく、伝熱性能としては良好であった。また、溝底部分４ｂ、４ｂ、４ｂ（図２参照）における大径管の肉厚ｔ１、ｔ２、ｔ３（図２参照）が薄くなったため、他の実施例２〜６に比べて１０〜３０％程度耐圧強度が低い。
【０１４２】
実施例２〜５は、伝熱性能、曲げ加工性、耐圧強度ともに優れていた。
実施例６は、他の実施例１〜５よりｔ／Ｔが大きく、大径管に形成された溝部が浅くなるため、各溝部４における大径管２（表面４Ａ）と各小径管３（円弧３Ａ）の接触長さが短くなり（図２参照）、大径管の突起部４ａ、４ａ（図１１参照）の密着状況は良好であった。そして、その他の部分で隙間が形成されたが、その隙間は大きいものではなく、伝熱性能は良好であった。また、溝部が浅いために小径の嵌合力が小さくなり、曲げ試験において１本の複合伝熱管より小径管が離脱した（曲げの外側になる小径管）。
【０１４３】
これらの結果から、伝熱性能、曲げ加工性、及び耐圧性をすべて満足するためにはｔ／Ｔが０．３〜０．７の範囲が好ましいことがわかる。
【０１４４】
（第２の実施例）実施例７、実施例８
（１）複合伝熱管の作製
以下の手順で、ｔ／Ｔが実施例１および実施例３と同じであり、大径管と小径管が樹脂を介して嵌合された複合伝熱管を各１本ずつ作製し、それぞれ実施例７および実施例８とした。
（１−１）大径管の溝部形成
使用した大径管およびピン、溝部形成手順は第１の実施例と同じである。
【０１４５】
（１−２）溝部が形成された大径管の焼鈍
第１の実施例と同じである。
【０１４６】
（１−３）樹脂の塗布
樹脂としてはポリエチレングリコールを用いた。樹脂を水で塗布しやすい濃度に希釈し、更に、溝部における樹脂の存在状態を確認するため、青インクで着色し、大径管に形成した溝部に塗布した。
【０１４７】
（１−４）小径管の嵌合
使用した小径管は第１の実施例と同じである。そして、第１の実施例と同様に小径管を嵌合し、溝部より押出された余分な樹脂をふき取った。
【０１４８】
（１−５）樹脂の硬化
小径管が嵌合した大径管を非酸化性雰囲気に保たれた２００℃の炉に装入し、所定時間（０．５時間）加熱し、樹脂を硬化させ、複合伝熱管を得た。
【０１４９】
（２）評価項目
ｔ／Ｔ、伝熱性能、曲げ加工性について、第１の実施例と同様な方法で評価し、その結果を表４に示した。
【０１５０】
【表４】

【０１５１】
（３）評価結果
実施例１の複合伝熱管では、溝底部分に相当する位置に隙間が形成されているのが観察された。そして、実施例１と同じ値のｔ／Ｔを有する実施例７の複合伝熱管は、隙間が存在した部分に樹脂が充填されており、大径管と小径管は直接的または樹脂により密着している。このため、伝熱性能は優れたものであった。また、樹脂が存在しても曲げ加工性においても良好であった。
【０１５２】
実施例３の複合伝熱管は隙間が微細で少ないものであった。そして、実施例３と同じ値のｔ／Ｔを有する実施例８の複合伝熱管は、微細な隙間部にも樹脂が存在していることが確認され、伝熱性能は優れたものであった。また、実施例７と同様に、樹脂が存在しても曲げ加工性においても良好であった。
【０１５３】
これらの結果より、大径管と小径管との間に樹脂を存在させることにより、熱抵抗となる空気層がなくなり、熱抵抗が減少するため、伝熱性能が優れたものとなる、また、曲げ加工性にも悪影響を及ぼさないことが分かった。
【０１５４】
（第３の実施例）実施例９〜実施例１１
（１）複合伝熱管の作製
以下の手順で、実施例８とｔ／Ｔが同じで、実施例８とは異なる樹脂（セラミックス）を介して大径管と小径管が嵌合された複合伝熱管を３本作製し、実施例９〜１１とした。
（１−１）大径管の溝部形成
使用した大径管およびピン、溝部形成手順は第１の実施例と同じである。
【０１５５】
（１−２）溝部が形成された大径管の焼鈍
第１の実施例と同じである。
【０１５６】
（１−３）樹脂（セラミックス）の塗布
塗布する樹脂（セラミックス）としてはＪＳＲ社製グラスカＨＰＣ７５０６溶液（固体での密度１．５×１０^３ｋｇ／ｍ^３）を使用した。このセラミックスは加熱して硬化させると有機無機ハイブリッドセラミックスとなる。そして、ＨＰＣ７５０６溶液を溶剤で適当な濃度に希釈し、大径管の溝部に塗布したものを実施例９、ＨＰＣ７５０６溶液に平均粒径１μｍのα−Ｆｅ_２Ｏ_３粒子を１５ｖｏｌ％加え、溶剤で適当な濃度に希釈し、大径管の溝部に塗布したものを実施例１０、ＨＰＣ７５０６溶液に３５０メッシュアンダーの電解銅粉を１０ｖｏｌ％加え、溶剤で適当な濃度に希釈し、大径管の溝部に塗布したものを実施例１１とした。
【０１５７】
（１−４）小径管の嵌合
使用した小径管は第１の実施例と同じである。そして、第１の実施例と同様にして小径管を嵌合し、嵌合部より押出された余分な樹脂（セラミックス）をふき取った。
（１−５）樹脂（セラミックス）の硬化
小径管が嵌合した大径管を非酸化性雰囲気に保たれた１００℃の炉に装入し、樹脂（セラミックス）を硬化させ、複合伝熱管を得た。
【０１５８】
（２）評価項目
ｔ／Ｔ、伝熱性能、曲げ加工性について、第１の実施例と同様な方法で評価し、その結果を表５に示した。
【０１５９】
【表５】

【０１６０】
（３）評価結果
表５に示すように、実施例９〜実施例１１のいずれの複合伝熱管においても、小径管と大径管との間の微細な隙間部には、セラミックス層または金属酸化物粒子（金属粒子）を含有するセラミックス層が存在し、熱抵抗となる空気層がなくなる。それにより、熱抵抗が減少するため、伝熱性能が優れるものであった。また、曲げ加工性にも悪影響を及ぼさないことが分かった。
【０１６１】
（第４の実施例）実施例１２〜実施例１５
（１）複合伝熱管の作製
以下の手順で、表７に示すようにｔ／Ｔを４段階に変化させ、大径管の管軸直交断面において管円周方向に６０°ずつ離れた位置に３本の小径管を嵌合させた複合伝熱管（実施例１２〜実施例１５）を各４本ずつ作製した。
【０１６２】
（１−１）大径管の溝部形成
大径管には表８のものを使用した。大径管の材質としては、ＪＩＳＨ３３００に規定された合金番号Ｃ１２０１のりん脱酸銅を使用した。また、溝部形成には表６に示すピンを使用した。また、溝部形成には図８（ｂ）において、下側のピン１０の位置はそのままとし、上側のピン１０、１０を下側のピン１０から大径管２の管円周方向に６０°ずつ離れた位置に配置したものを用いた。その他の点は第１の実施例と同様とした。
【０１６３】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管を脱脂し、ローラーハース炉を用いて非酸化雰囲気で大径管を焼鈍した。焼鈍後の大径管は軟化し、引張り強さは２４３〜２５０Ｎ／ｍｍ^２、０．２％耐力は７８〜８１Ｎ／ｍｍ^２、伸びは５１〜５３％、平均結晶粒径（管軸平行断面）は２３〜２５μｍとなった。
【０１６４】
（１−３）小径管の嵌合
小径管には表８のものを使用した。小径管の材質としては、ＪＩＳＨ３３００に規定された合金番号Ｃ１２２０のりん脱酸銅を使用した。大径管に形成された３本の溝部に３本の小径管をそれぞれ軽くはめ込み、３本の小径管が上側のロールに当るように圧延ロールに通した。これにより、大径管の管軸直交断面の管円周方向に６０°ずつ離れた位置に、３本の小径管が嵌合された複合伝熱管を作製した。
【０１６５】
（２）評価項目
前記で作製された４本の複合伝熱管の内１本について、長さ８０００ｍｍの溝部を８００ｍｍずつに切断し１０本の試料を作成し、ｔ／Ｔ、伝熱性能及び曲げ加工性を調査した。また、残りの３本を用いて耐圧強度を調査した。
（２−１）ｔ／Ｔ
図３に示すように、ｔは、３本の小径管３、３、３と嵌合している３本の溝部４、４、４の溝底部分４ｂ、４ｂ、４ｂの肉厚ｔ１、ｔ２、ｔ３の平均値とする。また、Ｔは、同図に示す、各小径管３と嵌合していない大径管２の所定位置での肉厚Ｔ１とする。長さ８０００ｍｍの溝部のうち、両端より８００ｍｍ及び４０００ｍｍの３箇所より厚さ１０ｍｍ程度の試料を採取し、管軸直交断面を光学顕微鏡で観察してそれぞれの位置における肉厚ｔ１、ｔ２、ｔ３、Ｔ１を測定し、それらの平均値よりｔ／Ｔを計算し、表７に示す。
【０１６６】
（２−２）伝熱性能
溝部における大径管と小径管との密着状況で評価する。前記の８００ｍｍずつに切断した１０本の試料において、両端部を除く９箇所の管軸直交断面で、溝部の大径管と小径管との密着状況を光学顕微鏡で観察した。その結果を表７に示す。また、大径管と小径管と間に生じた隙間が微細で少ないものを、伝熱性能が優れ「○」と、生じた隙間が大きくないものを、伝熱性能が良好で「△」と、生じた隙間が大きく多いものを、伝熱性能が劣る「×」と評価した。
【０１６７】
（２−３）曲げ加工性
曲げ試験により曲げ加工性を評価した。曲げ試験は、前記の長さ８００ｍｍに切断された試料を用いて行なった。試料は半径６０ｍｍの曲げ治具に沿わせてＵ字曲げし、大径管から小径管が外れることはないか評価した。なお、図３に示すように、複合伝熱管１の管軸直交断面において、一点鎖線（Ｙ−Ｙ線）が曲げの中立軸となる（３本の小径管３、３、３が曲げの内側になる）ように曲げた。ｎ＝５で調査を行い、小径管が外れたものの個数を記録した。その結果を表７に示す。
【０１６８】
（２−４）耐圧強度
第１の実施例の方法に同じ。その結果を表７に示す。
【０１６９】
【表６】

【０１７０】
【表７】

【０１７１】
【表８】

【０１７２】
（３）評価結果
表７に示すように、実施例１２は他の試料よりｔ／Ｔが小さく、大径管に形成された溝が深くなったため、嵌合により小径管にかぶさった大径管の突起部における密着は良好であった。そして、溝底部分に相当する位置に隙間が形成されたが、その隙間は大きいものではなく、伝熱性能は良好であった。また、溝底部分における大径管の肉厚が薄くなったため、他の試料に比べて耐圧強度が低い。
【０１７３】
実施例１３および実施例１４は、伝熱性能、曲げ加工性、耐圧強度とも優れたものであった。
【０１７４】
実施例１５は他の試料よりｔ／Ｔが大きく、大径管に形成された溝が浅くなるため、溝部における大径管と小径管の接触長さが短くなり、大径管の突起部の密着状況は良好であるが、その他の部分で隙間が形成された。その隙間は大きいものではなく、伝熱性能は良好であった。また、実施例１５は嵌合力は小さいが、曲げ断面において小径管が曲げの内側面に来るように曲げても、複合伝熱管より小径管が離脱したものはなかった。
【０１７５】
（第５の実施例）実施例１６
（１）複合伝熱管の作製
以下の手順で、銅合金からなる大径管の管軸直交断面の管円周方向に１２０°ずつ離れた位置（管軸直交断面における等間隔の位置）に小径管を３本嵌合させた複合伝熱管（実施例１６）を４本作製した。
【０１７６】
（１−１）大径管の溝形成
第１の実施例に同じ。但し、大径管には表９のものを使用し、その材質は、０．６５質量％Ｓｎ、０．０２７質量％Ｐ、０．３５質量％Ｚｎ、残部がＣｕの銅合金を使用した。
【０１７７】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管を脱脂し、ローラーハース炉を用いて非酸化雰囲気で大径管を焼鈍した。焼鈍後の大径管は軟化し、引張り強さは３２２Ｎ／ｍｍ^２、０．２％耐力は１２８Ｎ／ｍｍ^２、伸びは４３％、平均結晶粒径（管軸平行断面）は１５μｍとなった。
【０１７８】
（１−３）小径管の嵌合
小径管は表１のものを用い、嵌合の方法も第１の実施例に同じとした。
【０１７９】
（２）評価項目
第１の実施例に同じ。その結果を表１０に示す。
（３）評価結果
表１０に示すように、実施例１６の複合伝熱管は、伝熱性能、曲げ加工性とも優れたものであった。また、大径管に合金管を用いたため耐圧強度は、ｔ／Ｔがほぼ同じである実施例４の複合伝熱管に比べても大幅に向上していた。
【０１８０】
【表９】

【０１８１】
【表１０】

【０１８２】
（第６の実施例）実施例１７
（１）複合伝熱管の作製
以下の手順で、大径管及び小径管として、表１１に示す材質及び機械的性質のアルミニウム合金管またはアルミニウム管を用い、大径管の管軸直交断面における等間隔の位置に小径管を３本嵌合させた複合伝熱管（実施例１７）を１本作製した。
【０１８３】
（１−１）大径管の溝部形成
第１の実施例に同じ。但し、大径管には表１１のものを使用し、その材質は、ＪＩＳＨ４０００に規定された合金番号Ａ５０５２のＡｌ−Ｍｇ系合金を使用した。
【０１８４】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管を脱脂し、ローラーハース炉を用いて非酸化雰囲気で大径管を焼鈍した。焼鈍後の大径管は軟化し、引張り強さは１８７Ｎ／ｍｍ^２、０．２％耐力は８７Ｎ／ｍｍ^２、伸びは３１％となった。
【０１８５】
（１−３）小径管の嵌合
第１の実施例に同じ。但し、小径管には表１１のものを使用し、その材質としては、ＪＩＳＨ４０００に規定された合金番号Ａ１１００の純アルミニウムを使用した。
【０１８６】
（２）評価項目
第１の実施例に同じ。但し、耐圧試験は評価せず。その結果を表１２に示す。
【０１８７】
【表１１】

【０１８８】
【表１２】

【０１８９】
（３）評価結果
表１２に示すように、実施例１７の複合伝熱管は、伝熱性能、曲げ加工性とも優れたものであった。
【０１９０】
（第７の実施例）実施例１８
（１）複合伝熱管の作製
以下の手順で、大径管として内面溝付管を用いて、その大径管に３本の小径管を嵌合させた複合伝熱管（実施例１８）を４本作製した。
【０１９１】
（１−１）大径管の溝部形成
第１の実施例と同じ。但し、大径管には表１３のものを使用し、その材質はＪＩＳＨ３３００に規定された合金番号Ｃ１２２０のりん脱酸銅を使用した。また、内面の溝形状はリード角２５°、溝数５５、溝深さ０．２３ｍｍ、山頂角３０°のものを使用した。
【０１９２】
（２）溝部が形成された大径管の焼鈍
溝部が形成された大径管を脱脂し、ローラーハース炉を用いて非酸化雰囲気で大径管を焼鈍した。焼鈍後の大径管は軟化し、引張り強さは２２７Ｎ／ｍｍ^２、０．２％耐力は７０Ｎ／ｍｍ^２、伸びは４９％、平均結晶粒径（管軸平行断面）は２０μｍとなった。
【０１９３】
（１−３）小径管の嵌合
小径管は表１のものを用い、嵌合の方法も第１の実施例に同じとした。
（２）評価項目
第１の実施例に同じ。その結果を表１４に示す。
【０１９４】
【表１３】

【０１９５】
【表１４】

【０１９６】
（３）評価結果
表１４に示すように、実施例１８は、伝熱性能、曲げ加工性、耐圧強度とも優れたものであった。
【０１９７】
（第８の実施例）実施例１９〜実施例２７、比較例１、比較例２
（１） 複合伝熱管の作製
以下の手順で、特定の０．２％耐力を有する大径管に、特定の０．２％耐力を有する３本の小径管を嵌合した複合伝熱管（実施例１９〜実施例２７）を作製した。また、焼鈍を行わない大径管を用いた複合伝熱管（比較例１、比較例２）も作製した。
【０１９８】
（１−１）大径管の溝部形成
第１の実施例と同じ。但し、大径管には表１５のものを使用し、その材質としてはＪＩＳＨ３３００に規定された合金番号Ｃ１２０１のりん脱酸銅を用い、全長５２００ｍｍとした。また、ピンは表１６のものを使用し、このピンを大径管に押し当てた状態で、大径管の移動をＮｏ．Ｄ１〜Ｎｏ．Ｄ４では４回行い（５０００ｍｍ×４）、Ｄ５のみ６回（５０００ｍｍ×６）行い、管端１００ｍｍを除いた部分に溝部を形成した。そして、表１５のＮｏ．Ｄ３の大径管のみ４本、他の大径管は２本に、溝部を形成した。また、溝部形成の結果を表１７に示す。
【０１９９】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管（表１５のＮｏ．Ｄ１〜Ｎｏ．Ｄ５）を各２本ずつ脱脂し、ローラーハース炉を用いて非酸化雰囲気で焼鈍した。焼鈍後の大径管は軟化し、引張り強さ２０８〜２５０Ｎ／ｍｍ^２、０．２％耐力５６〜７７Ｎ／ｍｍ^２、伸び４９〜５３％、平均結晶粒径（管軸平行断面）２０〜３０μｍとなった。そして、表１５のＮｏ．Ｄ３の残りの２本は焼鈍を行わなかった。
【０２００】
（１−３）小径管の嵌合
小径管には表１８の２種類（Ｎｏ．Ｓ１、Ｓ２）を使用し、その材質はＪＩＳＨ３３００に規定された合金番号Ｃ１２０１のりん脱酸銅を使用した。そして、前記の焼鈍したＮｏ．Ｄ１〜Ｄ５の大径管及び焼鈍を行っていないＮｏ．Ｄ３の大径管に形成した３本の溝に、２種類（Ｎｏ．Ｓ１、Ｓ２）の小径管を３本それぞれ軽くはめ込み、第１の実施例と同様に圧延ロールに通す。これにより、大径管の管軸直交断面の等間隔の位置に３本の小径管が嵌合された複合伝熱管を作製した。
【０２０１】
（３）評価項目
第１の実施例に同じ。但し、曲げ加工性、耐圧強度を除く。その結果を表１９に示す。
【０２０２】
【表１５】

【０２０３】
【表１６】

【０２０４】
【表１７】

【０２０５】
【表１８】

【０２０６】
【表１９】

【０２０７】
（４）評価結果
表１９に示すように、実施例１９は、大径管の０．２％耐力が小さいため、溝部形成時にピンの当たる部分以外も変形を受けやすく、広めの幅（Ｖ字型に近い形状）の溝部が形成された。しかしながら、小径管を嵌合したとき大径管の突起部以外の部分で発生した隙間は大きいものではなく、伝熱性能は良好であった。また、小径管として軟質なもの（Ｓ２）を用いた実施例２０においても、圧延により小径管が変形したが、発生した隙間は大きいものではなく、伝熱性能は良好であった。
【０２０８】
実施例２１、実施例２３、実施例２５は、小径管として硬質なもの（Ｓ１）を嵌合したため、いずれも隙間の発生が少なく、伝熱性能は優れたものであった。また、実施例２２、実施例２４は、小径管として軟質なもの（Ｓ２）を嵌合したため、いずれも圧延により小径管が変形したが、発生した隙間は大きいものではなく、伝熱性能は良好であった。
【０２０９】
実施例２６、実施例２７は、大径管が硬質であるため溝部形成に手間取ったが、実施例２１〜実施例２５と同様に、発生した隙間は大きいものではなく、伝熱性能は良好であった。
【０２１０】
比較例１、比較例２は、大径管の焼鈍を行わなかったため、硬質な状態の大径管に小径管を嵌合することとなり、大径管の溝部に小径管が入りにくく、大径管突起部の小径管へのかぶさりも十分ではなかった。そのため、溝底部分に大きな隙間が多く形成され、伝熱性能は劣っていた。
【０２１１】
前記より、管外面に溝を形成する前の大径管として管軸方向の０．２％耐力σ_０．２が２００〜３７０Ｎ／ｍｍ^２であるものを用い、小径管として、０．２％耐力σ_０．２が２００Ｎ／ｍｍ^２以上のものを用いることが好ましいことが分かる。
【０２１２】
（第９の実施例）実施例２８〜実施例３３
（１）複合伝熱管の作製
以下の手順で、表２１に示す６段階にｔ／Ｔを変化させ、大径管の管軸直交断面の管円周方向に９０°ずつ離れた位置（管軸直交断面における等間隔の位置）に４本の小径管が嵌合された複合伝熱管（実施例２８〜３３）を各４本ずつ作製した。
【０２１３】
（１−１）大径管の溝部形成
大径管には表２０のものを使用した。大径管の材質としては、ＪＩＳＨ３３００に規定された合金番号Ｃ１２２０のりん脱酸銅を使用した。また、溝部形成には表２および図８（ａ）に示すピン１０を使用した。ピン１０を固定し、大径管２を移動させることにより大径管２の管軸直交断面で９０°ずつ離れた４箇所に溝部４、４、４、４を形成した。また、各溝部４の形成は、潤滑油を滴下しながら（図示せず）、大径管２全長に対し、両端部の１００ｍｍを除いた部分に各溝部４を形成した。その他は第１の実施例と同じ。
【０２１４】
（１−２）溝部が形成された大径管の焼鈍
第１の実施例と同じ。焼鈍後の引張り強さは２２０〜２３６Ｎ／ｍｍ^２、０．２％耐力は７１〜７４Ｎ／ｍｍ^２、伸びは５０〜５１．５％、平均結晶粒径（管軸平行断面）は２２〜２５μｍとなった。
【０２１５】
（１−３）小径管の嵌合
小径管には表２０のものを使用した。小径管の材質としては、ＪＩＳＨ３３００に規定された合金番号Ｃ１２２０のりん脱酸銅を使用した。図１０（ａ）に示すように、大径管２に形成された４本の溝部４、４、４、４に４本の小径管３、３、３、３をそれぞれ軽くはめ込み、圧延ロール１６、１６に通す。これにより、大径管２の管軸直交断面の９０°離れた位置に、４本の小径管３、３、３、３が嵌合された複合伝熱管１を作製した。
【０２１６】
（２）評価項目
前記で作製された４本の複合伝熱管の内１本について、長さ５０００ｍｍの溝部を５００ｍｍずつに切断して１０本の試料を作成し、ｔ／Ｔ、伝熱性能及び曲げ加工性を調査した。また、残りの３本を用いて耐圧強度を調査した。
（２−１）ｔ／Ｔ
図５に示すように、ｔは、小径管３、３、３、３と嵌合している４本の溝部４、４、４、４の溝底部分４ｂ、４ｂ、４ｂ、４ｂの肉厚ｔ１、ｔ２、ｔ３、ｔ４の平均値とする。また、Ｔは、同図に示す、小径管３、３、３、３と嵌合していない大径管２の４ヶ所の肉厚Ｔ１、Ｔ２、Ｔ３、Ｔ４の平均値とする。長さ５０００ｍｍの溝部のうち、両端より５００ｍｍ及び２５００ｍｍの３箇所より厚さ１０ｍｍ程度の試料を採取し、管軸直交断面を光学顕微鏡で観察してそれぞれの位置における肉厚ｔ１〜ｔ４、Ｔ１〜Ｔ４を測定し、それらの平均値よりｔ／Ｔを計算し、その結果を表２１に示す。
【０２１７】
（２−２）伝熱性能
第１の実施例と同じ。その結果を表２１に示す。
【０２１８】
（２−３）曲げ加工性
第１の実施例と同じ。その結果を表２１に示す。
【０２１９】
（２−４）耐圧強度
第１の実施例と同じ。その結果を表２１に示す。
【０２２０】
【表２０】

【０２２１】
【表２１】

【０２２２】
（３）評価結果
実施例２８は、他の実施例２９〜３３よりｔ／Ｔが小さく、大径管に形成された溝部が深くなったため、嵌合により小径管にかぶさった大径管の突起部４ａ、４ａ（図１１参照）が長く、この部分の密着状況は良好であった。そして、溝底部分４ｂ、４ｂ、４ｂ、４ｂ（図５参照）に相当する位置に隙間が形成されたが、その隙間は大きいものでなく、伝熱性能としては良好であった。また、溝底部分４ｂ、４ｂ、４ｂ、４ｂ（図５参照）における大径管の肉厚ｔ１、ｔ２、ｔ３、ｔ４（図５参照）が薄くなったため、他の実施例２９〜３３に比べて１０〜３０％程度耐圧強度が低い。
【０２２３】
実施例２９〜３２は、伝熱性能、曲げ加工性、耐圧強度ともに優れていた。
実施例３３は、他の実施例２８〜３２よりｔ／Ｔが大きく、大径管に形成された溝部が浅くなるため、各溝部４における大径管２（表面４Ａ）と各小径管３（円弧３Ａ）の接触長さが短くなり（図５参照）、大径管の突起部４ａ、４ａ（図１１参照）の密着状況は良好であった。そして、その他の部分で隙間が形成されたが、その隙間は大きいものではなく、伝熱性能は良好であった。また、溝部が浅いために小径の嵌合力が小さくなり、曲げ試験において２本の複合伝熱管より小径管が離脱した（曲げの外側になる小径管）。
【０２２４】
これらの結果から、伝熱性能、曲げ加工性、及び耐圧性をすべて満足するためにはｔ／Ｔが０．３〜０．７の範囲が好ましいことがわかる。
【０２２５】
（第１０の実施例）実施例３４、実施例３５
（１）複合伝熱管の作製
第２の実施例と同じ手順で、ｔ／Ｔが表２１の実施例２８および実施例３０と同じであり、大径管と小径管が樹脂を介して嵌合された複合伝熱管を各１本ずつ作製し、それぞれ実施例３４および実施例３５とした。
（１−１）大径管の溝部形成
使用した大径管およびピン、溝部形成手順は第９の実施例と同じである。
【０２２６】
（１−２）溝部が形成された大径管の焼鈍
第９の実施例と同じである。
【０２２７】
（１−３）樹脂の塗布
第２の実施例と同じ。
【０２２８】
（１−４）小径管の嵌合
使用した小径管は第９の実施例と同じである。そして、第９の実施例と同様に小径管を嵌合し、溝部より押出された余分な樹脂をふき取った。
【０２２９】
（１−５）樹脂の硬化
小径管が嵌合した大径管を非酸化性雰囲気に保たれた２００℃の炉に装入し、所定時間（０．５時間）加熱し、樹脂を硬化させ、複合伝熱管を得た。
【０２３０】
（２）評価項目
ｔ／Ｔ、伝熱性能、曲げ加工性について、第９の実施例と同様な方法で評価し、その結果を表２２に示した。
【０２３１】
【表２２】

【０２３２】
（３）評価結果
第９の実施例の実施例２８の複合伝熱管では、溝底部分に相当する位置に隙間が形成されているのが観察された。そして、実施例２８と同じ値のｔ／Ｔを有する実施例３４の複合伝熱管は、隙間が存在した部分に樹脂が充填されており、大径管と小径管は直接的または樹脂により密着している。このため、伝熱性能は優れたものであった。また、樹脂が存在しても曲げ加工性においても良好であった。
【０２３３】
実施例３０の複合伝熱管は隙間が微細で少ないものであった。そして、実施例３０と同じ値のｔ／Ｔを有する実施例３５の複合伝熱管は、微細な隙間部にも樹脂が存在していることが確認され、伝熱性能は優れたものであった。また、実施例３４と同様に、樹脂が存在しても曲げ加工性においても良好であった。
【０２３４】
これらの結果より、大径管と小径管との間に樹脂を存在させることにより、熱抵抗となる空気層がなくなり、熱抵抗が減少するため、伝熱性能が優れたものとなる、また、曲げ加工性にも悪影響を及ぼさないことが分かった。
【０２３５】
（第１１の実施例）実施例３６〜実施例３９
（１）複合伝熱管の作製
以下の手順で、表２４に示すようにｔ／Ｔを４段階に変化させ、大径管の管軸直交断面において管円周方向に６０°ずつ離れた位置に４本の小径管を嵌合させた複合伝熱管（実施例３６〜実施例３９）を各４本ずつ作製した。
【０２３６】
（１−１）大径管の溝部形成
大径管には表２３のものを使用した。大径管の材質としては、ＪＩＳＨ３３００に規定された合金番号Ｃ１２０１のりん脱酸銅を使用した。また、溝部形成には表６に示すピンを使用した。また、溝部形成には図８（ａ）において、下側のピン１０の位置はそのままとし、上側のピン１０、１０、１０を下側のピン１０から大径管２の管円周方向に６０°ずつ離れた位置に配置したものを用いた。その他の点は第１の実施例と同様とした。
【０２３７】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管を脱脂し、ローラーハース炉を用いて非酸化雰囲気で大径管を焼鈍した。焼鈍後の大径管は軟化し、引張り強さは２４５〜２５０Ｎ／ｍｍ^２、０．２％耐力は７９〜８１Ｎ／ｍｍ^２、伸びは５１〜５３％、平均結晶粒径（管軸平行断面）は２１〜２３μｍとなった。
【０２３８】
（１−３）小径管の嵌合
小径管には表２３のものを使用した。小径管の材質としては、ＪＩＳＨ３３００に規定された合金番号Ｃ１２２０のりん脱酸銅を使用した。大径管に形成された４本の溝部に４本の小径管をそれぞれ軽くはめ込み、４本の小径管が上側のロールに当るように圧延ロールに通した。これにより、大径管の管軸直交断面の管円周方向に６０°ずつ離れた位置に、４本の小径管が嵌合された複合伝熱管を作製した。
【０２３９】
（２）評価項目
前記で作製された４本の複合伝熱管の内１本について、長さ８０００ｍｍの溝部を８００ｍｍずつに切断し１０本の試料を作成し、ｔ／Ｔ、伝熱性能及び曲げ加工性を調査した。また、残りの３本を用いて耐圧強度を調査した。
（２−１）ｔ／Ｔ
図６に示すように、ｔは、４本の小径管３、３、３、３と嵌合している４本の溝部４、４、４、４の溝底部分４ｂ、４ｂ、４ｂ、４ｂの肉厚ｔ１、ｔ２、ｔ３、ｔ４の平均値とする。また、Ｔは、同図に示す、各小径管３と嵌合していない大径管２の所定位置での肉厚Ｔ１とする。長さ８０００ｍｍの溝部のうち、両端より８００ｍｍ及び４０００ｍｍの３箇所より厚さ１０ｍｍ程度の試料を採取し、管軸直交断面を光学顕微鏡で観察してそれぞれの位置における肉厚ｔ１、ｔ２、ｔ３、ｔ４、Ｔ１を測定し、それらの平均値よりｔ／Ｔを計算し、表２４に示す。
【０２４０】
（２−２）伝熱性能
第４の実施例と同じ。その結果を表２４に示す。
【０２４１】
（２−３）曲げ加工性
第４の実施例と同じ。その結果を表２４に示す。
【０２４２】
（２−４）耐圧強度
第１の実施例の方法に同じ。その結果を表２４に示す。
【０２４３】
【表２３】

【０２４４】
【表２４】

【０２４５】
（３）評価結果
表２４に示すように、実施例３６は他の試料よりｔ／Ｔが小さく、大径管に形成された溝が深くなったため、嵌合により小径管にかぶさった大径管の突起部における密着は良好であった。そして、溝底部分に相当する位置に隙間が形成されたが、その隙間は大きいものではなく、伝熱性能は良好であった。また、溝底部分における大径管の肉厚が薄くなったため、他の試料に比べて耐圧強度が低い。
【０２４６】
実施例３７および実施例３８は、伝熱性能、曲げ加工性、耐圧強度とも優れたものであった。
【０２４７】
実施例３９は他の試料よりｔ／Ｔが大きく、大径管に形成された溝が浅くなるため、溝部における大径管と小径管の接触長さが短くなり、大径管の突起部の密着状況は良好であるが、その他の部分で隙間が形成された。その隙間は大きいものではなく、伝熱性能は良好であった。また、実施例３９は嵌合力は小さいが、曲げ断面において小径管が曲げの内側面に来るように曲げても、複合伝熱管より小径管が離脱したものはなかった。
【０２４８】
（第１２の実施例）実施例４０
（１）複合伝熱管の作製
以下の手順で、銅合金からなる大径管の管軸直交断面の管円周方向に９０°ずつ離れた位置（管軸直交断面における等間隔の位置）に小径管を４本嵌合させた複合伝熱管（実施例４０）を４本作製した。
【０２４９】
（１−１）大径管の溝部形成
第９の実施例に同じ。但し、大径管には表２５のものを使用し、その材質は、０．６５質量％Ｓｎ、０．０２７質量％Ｐ、０．３５質量％Ｚｎ、残部がＣｕの銅合金を使用した。
【０２５０】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管を脱脂し、ローラーハース炉を用いて非酸化雰囲気で大径管を焼鈍した。焼鈍後の大径管は軟化し、引張り強さは３１１Ｎ／ｍｍ^２、０．２％耐力は１１３Ｎ／ｍｍ^２、伸びは４５％、平均結晶粒径（管軸平行断面）は１５μｍとなった。
【０２５１】
（１−３）小径管の嵌合
小径管は表２０のものを用い、嵌合の方法も第９の実施例に同じ。
【０２５２】
（２）評価項目
第９の実施例に同じ。その結果を表２６に示す。
（３）評価結果
表２６に示すように、実施例４０の複合伝熱管は、伝熱性能、曲げ加工性とも優れたものであった。また、大径管に強度の高い合金管を用いたため耐圧強度は、ｔ／Ｔがほぼ同じである実施例３１の複合伝熱管に比べても大幅に向上していた。
【０２５３】
【表２５】

【０２５４】
【表２６】

【０２５５】
（第１３の実施例）実施例４１
（１）複合伝熱管の作製
以下の手順で、大径管として内面溝付管を用いて、その大径管の管円周方向に等間隔に４本の小径管を嵌合させた複合伝熱管（実施例４１）を４本作製した。
【０２５６】
（１−１）大径管の溝部形成
第９の実施例と同じ。但し、大径管には表２７のものを使用し、その材質はＪＩＳＨ３３００に規定された合金番号Ｃ１２２０のりん脱酸銅を使用した。また、内面の溝形状はリード角３５°、溝数５５、溝深さ０．２３ｍｍ、山頂角２５°のものを使用した。
【０２５７】
（２）溝部が形成された大径管の焼鈍
第９の実施例と同じ。焼鈍後の大径管は軟化し、引張り強さは２２０Ｎ／ｍｍ^２、０．２％耐力は６９Ｎ／ｍｍ^２、伸びは５０％、平均結晶粒径（管軸平行断面）は１８μｍとなった。
【０２５８】
（１−３）小径管の嵌合
小径管は表２０のものを用い、嵌合の方法も第９の実施例に同じ。
（２）評価項目
第９の実施例に同じ。その結果を表２８に示す。
【０２５９】
【表２７】

【０２６０】
【表２８】

【０２６１】
（３）評価結果
表２８に示すように、実施例４１は、伝熱性能、曲げ加工性、耐圧強度とも優れたものであった。
【０２６２】
（第１４の実施例）実施例４２〜実施例５１、比較例３、比較例４
（１） 複合伝熱管の作製
以下の手順で、特定の０．２％耐力を有する大径管に、特定の０．２％耐力を有する４本の小径管を嵌合した複合伝熱管（実施例４２〜実施例５１）を作製した。また、焼鈍を行わない大径管を用いた複合伝熱管（比較例３、比較例４）も作製した。
【０２６３】
（１−１）大径管の溝部形成
第９の実施例と同じ。但し、大径管には表２９のものを使用し、その材質としてはＪＩＳＨ３３００に規定された合金番号Ｃ１２２０のりん脱酸銅を用い、全長５２００ｍｍとした。また、ピンは表３０のものを使用し、このピンを大径管に押し当てた状態で、大径管の移動をＮｏ．Ｄ６〜Ｎｏ．Ｄ９では４回行い（５０００ｍｍ×４）、Ｎｏ．Ｄ１０のみ６回（５０００ｍｍ×６）行い、管端１００ｍｍを除いた部分に溝部を形成した。そして、表２９のＮｏ．Ｄ８の大径管のみ４本、他の大径管は２本に、溝部を形成した。また、溝部形成の結果を表３１に示す。
【０２６４】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管（表２９のＮｏ．Ｄ６〜Ｎｏ．Ｄ１０）を各２本ずつ脱脂し、ローラーハース炉を用いて非酸化雰囲気で焼鈍した。焼鈍後の大径管は軟化し、引張り強さ２１０〜２４３Ｎ／ｍｍ^２、０．２％耐力６６〜８３Ｎ／ｍｍ^２、伸び４９〜５１％、平均結晶粒径（管軸平行断面）２０〜３０μｍとなった。そして、表２９のＮｏ．Ｄ８の残りの２本は焼鈍を行わなかった。
【０２６５】
（１−３）小径管の嵌合
小径管には表１８の２種類（Ｎｏ．Ｓ１、Ｓ２）を使用した。そして、前記の焼鈍したＮｏ．Ｄ６〜Ｎｏ．Ｄ１０の大径管及び焼鈍を行っていないＮｏ．Ｄ８の大径管に形成した４本の溝に、２種類（Ｎｏ．Ｓ１、Ｓ２）の小径管を４本それぞれ軽くはめ込み、第９の実施例と同様に圧延ロールに通す。これにより、大径管の管軸直交断面の等間隔の位置に４本の小径管が嵌合された複合伝熱管を作製した。
【０２６６】
（３）評価項目
第９の実施例に同じ。但し、曲げ加工性、耐圧強度を除く。その結果を表３２に示す。
【０２６７】
【表２９】

【０２６８】
【表３０】

【０２６９】
【表３１】

【０２７０】
【表３２】

【０２７１】
（４）評価結果
表３２に示すように、実施例４２は、大径管の０．２％耐力が小さいため、溝部形成時にピンの当たる部分以外も変形を受けやすく、広めの幅（Ｖ字型に近い形状）の溝部が形成された。しかしながら、小径管を嵌合したとき大径管の突起部以外の部分で発生した隙間は大きいものではなく、伝熱性能は良好であった。また、小径管として軟質なもの（Ｓ２）を用いた実施例４３においても、圧延により小径管が変形したが、発生した隙間は大きいものではなく、伝熱性能は良好であった。
【０２７２】
実施例４４、実施例４６、実施例４８は、小径管として硬質なもの（Ｓ１）を嵌合したため、いずれも隙間の発生が少なく、伝熱性能は優れたものであった。また、実施例４５、実施例４７、実施例４９は、小径管として軟質なもの（Ｓ２）を嵌合したため、いずれも圧延により小径管が変形したが、発生した隙間は大きいものではなく、伝熱性能は良好であった。
【０２７３】
実施例５０、実施例５１は、大径管が硬質であるため溝部形成に手間取ったが、実施例４４〜実施例４９と同様に、発生した隙間は大きいものではなく、伝熱性能は良好であった。
【０２７４】
比較例３、比較例４は、大径管の焼鈍を行わなかったため、硬質な状態の大径管に小径管を嵌合することとなり、大径管の溝部に小径管が入りにくく、小径管が変形し、大径管突起部の小径管へのかぶさりも十分ではなかった。そのため、溝底部分に大きな隙間が多く形成され、伝熱性能は劣っていた。
【０２７５】
前記より、管外面に溝部を形成する前の大径管として管軸方向の０．２％耐力σ_０．２が２００〜３７０Ｎ／ｍｍ^２であるものを用い、小径管として、０．２％耐力σ_０．２が２００Ｎ／ｍｍ^２以上のものを用いることが好ましいことが分かる。
【０２７６】
（第１５の実施例）実施例５２〜実施例５４
（１）複合伝熱管の作製
以下の手順で、管軸直交断面における小径管と大径管の接触長さを変化させて嵌合した複合伝熱管を各２本ずつ作製し、それぞれ実施例５２〜実施例５４とした。
【０２７７】
（１−１）大径管の溝部形成
使用した大径管およびピンは第９の実施例と同じである。ピンの押し当て荷重及び移動回数を変化させることにより、溝深さを３種類に変化させ、溝の最も浅いものを実施例５２、溝の最も深いものを実施例５４とした。
【０２７８】
（１−２）溝部が形成された大径管の焼鈍
第９の実施例と同じである。
【０２７９】
（１−３）小径管の嵌合
使用した小径管は第９の実施例と同じである。そして、第９の実施例と同様にして小径管を嵌合した。
【０２８０】
（２）評価項目
嵌合部における小径管の接触長さは発明の実施の形態で述べた方法で測定した。伝熱性、曲げ加工性については、第９の実施例と同様な方法で評価し、その結果を表３３に示した。
【０２８１】
【表３３】

【０２８２】
（３）評価結果
表３３に示すように、小径管の接触長さは実施例５２の複合伝熱管が５２％、実施例５３の複合伝熱管が５５％、実施例５４の複合伝熱管が８０％であった。実施例５２〜実施例５４のいずれの複合伝熱管においても、小径管が大径管に正しく嵌合されており、伝熱性能が優れるものであった。曲げ加工性は、小径管の接触長さが５５％未満である実施例５２において、５本中２本の小径管のはずれが発生したが、小径管の接触長さが５５％以上の実施例５３及び実施例５４の複合伝熱管においては良好であった。このことより、特に曲げ加工を行う場合には小径管の接触長さが５５％以上であることが好ましいことがわかる。
【０２８３】
更に、各実施例の残りの１本の複合伝熱管を用いて拡管試験を行った。実施例５２の複合伝熱管の両端部に拡管プラグを挿入して内径が１２ｍｍとなるように拡管したところ、割れが発生することなく拡管が可能であった。実施例５２及び実施例５３の複合伝熱管をローラーハース炉により非酸化雰囲気で焼鈍した。焼鈍後の複合伝熱管の両端部に拡管プラグを挿入して内径が１２ｍｍとなるように拡管したところ、やはり割れが発生することなく拡管が可能であった。
【０２８４】
（第１６の実施例）実施例５５〜実施例６２
（１）複合伝熱管の作製
以下の手順で、表３５に示すようにｔ／Ｔを５段階に変化させ、大径管の管軸直交断面の９０°離れた位置に４本の小径管を嵌合させた、図１３に示すようならせん状の巻回部が形成された複合伝熱管（実施例５５〜実施例６２）を各４本ずつ作製した。
【０２８５】
（１−１）大径管の溝部形成
使用したピン、溝部形成手順は第９の実施例と同じ。大径管は表３４のものを使用した。
【０２８６】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管を脱脂し、ローラーハース炉を用いて非酸化雰囲気で大径管を焼鈍した。焼鈍後の大径管は軟化し、引張り強さ２３１〜２３８Ｎ／ｍｍ^２、０．２％耐力７１〜７５Ｎ／ｍｍ^２、伸び５０〜５２％、平均結晶粒径２５μｍ（管軸平行断面）となった。
【０２８７】
（１−３）小径管の嵌合
４本の小径管には表３４のものを使用。嵌合方法は第９の実施例と同じとした。
【０２８８】
（１−４）小径管が嵌合された大径管の焼鈍
実施例５８、実施例５９は、４本の小径管を嵌合した後、前記（１−２）と同じ条件で焼鈍を行った。焼鈍により大径管は引張り強さ２２８Ｎ／ｍｍ^２、０．２％耐力７０Ｎ／ｍｍ^２、伸び５１％、小径管は引張り強さ２６０Ｎ／ｍｍ^２、０．２％耐力１４３Ｎ／ｍｍ^２、伸び４５％に軟化した。また、いずれも管軸平行方向の断面で観察した平均結晶粒径（切断法）は約２５μｍであった。
【０２８９】
（１−５）らせん状複合伝熱管の作製
前記（１−３）、（１−４）において製作した各試料４本を、図１３、図１４（ａ）に示すように、４本の小径管が大径管に嵌合されている部分の全長をらせん状に２０回巻回し、巻回部の最小内径ＩＤが１５０ｍｍ、平均ピッチｐが約１３．０ｍｍのらせん状複合伝熱管を各４本ずつ作製した。なお、実施例５６、実施例５８、実施例６０については（１−２）と同一な条件で焼鈍を行なった。
【０２９０】
（２）評価項目
前記で作製された４本のらせん状複合伝熱管の内１本で、ｔ／Ｔおよび伝熱性能、また、残りの３本で小径管の離脱および耐圧強度を調査した。
（２−１）ｔ／Ｔ
らせん状複合伝熱管の巻回部の端部、中央部及び下端部より試験片を切出し、第９の実施例と同様な方法で評価し、その結果を表３５に示した。
【０２９１】
（２−２）伝熱性能
第９の実施例と同様な方法で評価し、その結果を表３５に示した。
【０２９２】
（２−３）小径管の離脱
らせん状複合伝熱管の外観を目視観察し、大径管より小径管が浮いている箇所、小径管が外れている箇所があるか観察した（ｎ＝３）。
【０２９３】
（２−４）耐圧強度
前記（２−３）の評価の後、大径管に水を充填してハンドポンプで徐々に加圧し、小径管が大径管から離脱し始める圧力をブルドン管ゲージで読取った。ｎ＝３の平均値で評価を行った。
【０２９４】
【表３４】

【０２９５】
【表３５】

【０２９６】
（３）評価結果
実施例５５は他の試料よりｔ／Ｔが小さく、大径管に形成された溝が深くなったため、嵌合により小径管にかぶさった大径管の溝エッジ部が長く、この部分の密着状況は良好であった。そして、溝底部に相当する位置にやや大きな隙間が形成されているのが観察されが、伝熱性能としては良好であった。また、大径管のかぶさり代が大きいため、コイルに成型しても小径管の離脱は発生しなかった。嵌合部における大径管の肉厚が薄くなったため、他の試料に比べて１０〜３０％程度耐圧強度が低かった。
【０２９７】
また、実施例５６〜実施例６１は、焼鈍無し及び焼鈍有りとも小径管が大径管に強固に嵌合されていることから伝熱性能は良好であり、いずれも小径管の離脱は発生しなかった。また、耐圧強度も良好であった。
【０２９８】
また、実施例５６、実施例５８、実施例６０の焼鈍２を施した試料は、巻回後の焼鈍により残留応力が除去され、太径管と小径管が良く密着したため、耐圧強度は他の試料に比べ高かった。
【０２９９】
また、実施例６２は、他の試料よりｔ／Ｔが大きく、大径管に形成された溝が浅くなるため、管軸直交断面の嵌合部における大径管と小径管の接触長さが短くなり、大径管の溝エッジ部の密着状況は良好であるが、その他の部分でやや隙間の大きい部分が見られた。しかしながら、伝熱性能としては良好であった。また、大径管による小径管の嵌合力が小さいため、らせん状に巻回したときに小径管の離脱がわずかに発生し、耐圧強度が低下する傾向にあった。
【０３００】
また、これらの結果から、伝熱性能、曲げ加工性、及び耐圧性をすべて満足するためにはｔ／Ｔが０．３〜０．７の範囲が望ましいことがわかる。また、らせん状の巻回による小径管の離脱、伝熱性能及び耐圧強度上昇させるには、らせん状の巻回後の焼鈍が効果的であることがわかった。
【０３０１】
（第１７の実施例）実施例６３
（１）複合伝熱管の作製
以下の手順で、大径管の管軸直交断面の６０°離れた位置に４本の小径管を嵌合させた、らせん状の巻回部が形成されたらせん状複合伝熱管（実施例６３）を作製した。
【０３０２】
（１−１）大径管の溝部形成
大径管には表３６のものを使用した。また、溝部形成には表３７のピンを使用し、上側のピンの位置はそのままとし、下側のピンを上側のピンから大径管の管円周方向に６０°離れた位置に配置したものを用いた。その他の点は第１６の実施例と同じである。
【０３０３】
【表３６】

【０３０４】
【表３７】

【０３０５】
（１−２）溝部が形成された大径管の焼鈍
溝部が形成された大径管を脱脂し、ローラーハース炉を用いて非酸化雰囲気で大径管を焼鈍した。焼鈍後の大径管は軟化し、引張り強さ２５０Ｎ／ｍｍ^２、０．２％耐力８１Ｎ／ｍｍ^２、伸び５３％、平均結晶粒径２３μｍ（管軸平行断面）となった。
【０３０６】
（１−３）小径管の嵌合
４本の小径管が上側のロールに当たるように圧延ロールに通した。その他の点は第１６の実施例と同じ。
【０３０７】
（１−４）小径管が嵌合された大径管の焼鈍
焼鈍は行なわなかった。
【０３０８】
（１−５）らせん状複合伝熱管の作製
第１６の実施例と同じ。巻回後の焼鈍も行った。そして、作製されたらせん状複合伝熱管を、第１６の実施例と同様に評価した結果、ｔ／Ｔが０．３〜０．７の範囲内で、伝熱性能、小径管の離脱、耐圧強度も良好であった。
【０３０９】
（第１８の実施例）実施例６４
（１）複合伝熱管の作製
以下の手順で、大径管の管軸直交断面の９０°離れた位置に小径管を嵌合させた、図１５に示すような渦巻状の巻回部が二つ形成された複合伝熱管（実施例６４）を作製した。
【０３１０】
（１−１）大径管の溝部形成
第１６の実施例と同じである。
【０３１１】
（１−２）溝部が形成された大径管の焼鈍
第１６の実施例と同じである。
【０３１２】
（１−３）小径管の嵌合
第１６の実施例と同じである。
【０３１３】
（１−４）小径管が嵌合された大径管の焼鈍
焼鈍は行なわなかった。
【０３１４】
（１−５）渦巻状複合伝熱管の作製
前記（１−３）において製作した試料を、図１５、図１６（ａ）に示すように、４本の小径管が大径管に嵌合されている部分の全長を渦巻状に巻回直径が縮径する方向に７回巻回し、引き続いて、巻回直径が拡径する方向に７回巻回し、二つの巻回部６１ｋ、６１ｋの最小内径ＩＤが２００ｍｍ、最大外径ＯＤが４００ｍｍ、平均ピッチｐが約１３．５ｍｍの渦巻状複合伝熱管を作製した。なお、巻回後、第１６の実施例と同一な条件で焼鈍を行なった。
【０３１５】
（２）評価項目（伝熱性能）
作製した渦巻状複合伝熱管の大径管に流量１．１６ｋｇ／ｍｉｎの水を流し、４本の小径管に１１．５ＭＰａのＣＯ_２を流した。この渦巻状複合伝熱管を１０００時間運転し、運転中の入口温度（大径管）に対する出口温度（大径管）の変化を見ることにより、伝熱性能を確認した。
【０３１６】
（３）評価結果
大径管の入口温度に対する出口温度は常に安定していた。
【０３１７】
（第１９の実施例）実施例６５
（１）複合伝熱管の作製
以下の手順で、大径管の管軸直交断面の９０°離れた位置に４本の小径管を嵌合させた、渦巻状の巻回部が一つ形成された複合伝熱管（実施例６５）を作製した。
【０３１８】
（１−１）大径管の溝部形成
第１８の実施例と同じである。大径管および小径管の長さは５０００ｍｍとする。
【０３１９】
（１−２）溝部が形成された大径管の焼鈍
第１８の実施例と同じである。
【０３２０】
（１−３）小径管の嵌合
第１８の実施例と同じである。
【０３２１】
（１−４）小径管が嵌合された大径管の焼鈍
焼鈍は行なわなかった。
【０３２２】
（１−５）渦巻状複合伝熱管の作製
第１８の実施例と同様に、４本の小径管が大径管に嵌合されている部分の全長を渦巻状に巻回直径が縮径する方向に７回巻回し、巻回部の最小内径が２００ｍｍ、最大外径が４００ｍｍ、平均ピッチｐが約１３．５ｍｍの渦巻状複合伝熱管を作製した。なお、巻回後、第１８の実施例と同一な条件で焼鈍を行なった。
【０３２３】
（２）評価項目（伝熱性能）
第１８の実施例と同じである。
【０３２４】
（３）評価結果
大径管の入口温度に対する出口温度は常に安定していた。
【０３２５】
（第２０の実施例）実施例６６
（１）複合伝熱管の作製
以下の手順で、第１９の実施例と同様の渦巻状複合伝熱管を二つ作製し、それぞれを結合した複合伝熱管（実施例６６）を作製した。
【０３２６】
（１−１）大径管の溝部形成
第１９の実施例と同じである。
【０３２７】
（１−２）溝部が形成された大径管の焼鈍
第１９の実施例と同じである。
【０３２８】
（１−３）小径管の嵌合
第１９の実施例と同じである。
【０３２９】
（１−４）小径管が嵌合された大径管の焼鈍
焼鈍は行なわなかった。
【０３３０】
（１−５）渦巻状複合伝熱管の作製
第１９の実施例と同じ。作製された二つの渦巻状複合伝熱管の一方の管端部を拡管し、それぞれの管端部をロウ付けにより結合した。
【０３３１】
（２）評価項目（伝熱性能）
第１９の実施例と同じである。
【０３３２】
（３）評価結果
大径管の入口温度に対する出口温度は常に安定していた。また、ロウ付け部からの漏洩も認められなかった。
【０３３３】
【発明の効果】
以上説明したような構成であるため、本発明にかかる複合伝熱管においては、以下に示す優れた効果を奏する。
【０３３４】
複合伝熱管は、小径管と隣接する大径管の溝部の表面が、小径管の円弧と等しい円弧を有するものであるため、溝部の表面に小径管が密着し、大径管と小径管の接触部分の面積（伝熱面積）が増大すると共に、大径管と小径管が強固に嵌合され、溝部から小径管が外れる（抜ける）ことを抑制することができる。そのため、複合伝熱管は、伝熱性能が所望となるものを適切に製造でき生産性に優れる。また、複合伝熱管は、伝熱性能が良く、かつ耐圧強度も十分で、コンパクトに製造できるため、当該複合伝熱管を用いる冷蔵庫などの機器が小型化できる。
【０３３５】
また、複合伝熱管は、大径管および小径管の両端部の外径を所定範囲とすることにより、嵌合部における伝熱性能がさらに向上し、小型化されると共に、熱交換器に組み込む際の他の管との接合が容易となり都合がよい。
【０３３６】
また、複合伝熱管は、大径管は、小径管と嵌合している溝部の溝底部分の肉厚をｔ、小径管と嵌合していない部分の肉厚をＴとするとき、ｔ／Ｔの値が０．３〜０．７である複合伝熱管とすることで、大径管への小径管の嵌合がしやすくなり、大径管と小径管との間に隙間が形成されにくくなると共に、溝底部分が大径管の内圧に対向しうる応力を有し、嵌合された小径管が大径管から押出されるのが抑制される。さらに、大径管と小径管との相互の伝熱性能が向上されると共に、曲げ加工性についても向上でき、かつ、小径管の円弧と等しくなるように、大径管の溝部の表面の円弧を形成することができる。
【０３３７】
また、複合伝熱管は、複合伝熱管の管軸直交断面における小径管と大径管との見かけ上の接触長さを所定長さ以上とすることにより、大径管と小径管との伝熱面積がさらに増大し、大径管への小径管の嵌合力もさらに増大する。
【０３３８】
また、複合伝熱管は、大径管の管軸直交断面における等間隔の位置に小径管を配置することにより、大径管と小径管との間の伝熱効率が向上すると共に、大径管に小径管を収容するための溝部を形成、およびその溝部への小径管の圧延嵌合の作業性がよく生産性に優れる。
【０３３９】
また、複合伝熱管は、大径管の内面に管軸方向に平行な溝またはらせん状の溝が形成されていることにより、大径管内の伝熱面積がさらに増大し、複合伝熱管の伝熱性能がさらに向上する。
【０３４０】
さらに、複合伝熱管は、樹脂を介して大径管と小径管が嵌合されることにより、大径管と小径管の接触する面に形成される微細な隙間にも前記樹脂が充填され、接触面から熱伝導率の低い空気を排除し、大径管と小径管の密着度合いがさらに高まり、大径管と小径管との伝熱面積がさらに増大し、大径管への小径管の嵌合力もさらに増大する。
【０３４１】
また、複合伝熱管は、大径管および／または小径管が、無酸素銅またはりん脱酸銅から形成されることにより、大径管および／または小径管の熱伝導率、耐食性、塑性加工性（嵌合、曲げ等）、耐圧強度が向上すると共に、熱交換器に組み込む際のロウ・はんだ付け性が向上する。
【０３４２】
また、複合伝熱管は、らせん状または渦巻状の巻回部を形成することにより、複合伝熱管の伝熱面積が増大すると共に、コンパクト化できる。それにより、熱交換器内に設置しやすくなると共に、安定して設置することができる。また、大径管の管軸直交断面における外形形状を扁平円形にすることにより、複合伝熱管がさらにコンパクトになる。
【０３４３】
さらに、複合伝熱管の製造方法は、溝部形成工程と、焼鈍工程と、圧延嵌合工程とを含む、または、さらに樹脂塗布工程および樹脂硬化工程を含むため、または、さらに巻回工程、拡管工程、および焼鈍工程の少なくとも１つを行うため、伝熱性能が所望となる、耐圧強度も十分で、コンパクトな複合伝熱管を適切に製造できる。
【図面の簡単な説明】
【図１】（ａ）本発明にかかる３本の小径管を備える複合伝熱管の側面図、（ｂ）は溝部の端部を示めす部分切断斜視図である。
【図２】本発明にかかる複合伝熱管の図１のＸ−Ｘ線の断面図である。
【図３】本発明にかかる複合伝熱管の図２の他の実施形態の断面図である。
【図４】本発明にかかる複合伝熱管の図２の他の実施形態の断面図である。
【図５】本発明にかかる４本の小径管を備える複合伝熱管の断面図である。
【図６】本発明にかかる複合伝熱管の図５の他の実施形態の断面図である。
【図７】本発明にかかる複合伝熱管の大径管の４箇所に溝部を形成する溝部形成工程を模式的に示す管軸平行断面図である。
【図８】本発明にかかる複合伝熱管の大径管に溝部を形成する溝部形成工程を模式的に示す管軸直交断面図で、（ａ）は溝部が４箇所の場合、（ｂ）は溝部が３箇所の場合である。
【図９】本発明にかかる複合伝熱管の大径管に４本の小径管を嵌合する圧延嵌合工程を模式的に示す管軸平行断面図である。
【図１０】本発明にかかる複合伝熱管の大径管に小径管を嵌合する圧延嵌合工程を模式的に示す管軸直交断面図で、（ａ）は小径管が４本の場合、（ｂ）は小径管が３本の場合である。
【図１１】（ａ）は本発明にかかる図１０の嵌合前の溝部の部分拡大断面図、（ｂ）は嵌合後の溝部の部分拡大断面図、（ｃ）は（ｂ）の他の実施形態の部分拡大断面図である。
【図１２】本発明にかかる複合伝熱管を使用した熱交換器の構成を模式的に示す説明図である。
【図１３】本発明にかかるらせん状の巻回部が形成された複合伝熱管の斜視図である。
【図１４】（ａ）は図７のＣ−Ｃ線の断面図、（ｂ）、（ｃ）は図７の他の実施形態を示す部分断面図である。
【図１５】本発明にかかる渦巻状の巻回部が形成された複合伝熱管の斜視図である。
【図１６】（ａ）は図９のＤ−Ｄ線の断面図、（ｂ）は図９の他の実施形態を示す部分断面図である。
【図１７】従来の複合伝熱管の断面図である。
【図１８】（ａ）、（ｂ）は他の従来の複合伝熱管の断面図である。
【図１９】従来の他の複合伝熱管の斜視図である。
【符号の説明】
１、３１、４１、５１、６１、７１ 複合伝熱管
２、５２、７２ 大径管
２ａ 両端部
３、５３、７３ 小径管
３ａ 両端部
３Ａ 円弧
４ 溝部
４ａ 突起部
４ｂ 溝底部分
４Ａ 表面
５ 樹脂
３１ｋ、４１ｋ、５１ｋ、６１ｋ、７１ｋ 巻回部
６１ｉ、７１ｉ 移行部
１０ ピン
１１ 溝加工部
１１ａ 溝加工部先端
１２ 把持部
１３ 繋ぎ部
１４ 肩部
１５ スリーブ
１６ 圧延ロール
２０ 熱交換器
２１ 圧縮機
２２ 放熱器
２３ 冷却器
Ａ 複合化区間Ｂ以外の部分
Ｂ 複合化区間
θ 角度
ｄ 外径
ＩＤ 最小内径
ＯＤ 最大外径
Ｈ 高さ
ａ 管外径
ｐ 間隔[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to, for example, a heat transfer tube used for a heat exchanger such as a refrigerator, a freezer, a water heater, and a floor heater. More specifically, the present invention relates to a heat transfer tube flowing between a large-diameter tube and a small-diameter tube through a tube wall. The present invention relates to a composite heat transfer tube that performs heat exchange and a method for manufacturing the same.
[0002]
[Prior art]
Generally, as a configuration of a composite heat transfer tube for a heat exchanger, a configuration in which one large-diameter tube and one small-diameter tube are in contact with the outer surface of the large-diameter tube is known. In a composite heat transfer tube of a refrigerator or a freezer heat exchanger, a refrigerant such as Freon as a heat medium or an alternative CFC flows through the large-diameter tube and the small-diameter tube, and flows through the large-diameter tube and the small-diameter tube. Heat is exchanged between the two. In the composite heat transfer tube of the heat exchanger for a water heater, water is contained in a large-diameter tube, and CO is contained in a small-diameter tube. ₂ And the like. Further, in the composite heat transfer tube of the floor heating heat exchanger, water flows through the large-diameter tube, and refrigerant such as Freon or alternative Freon flows through the small-diameter tube.
[0003]
As a specific example of the composite heat transfer tube having the above-described configuration, there has been proposed a composite heat transfer tube in which a small-diameter pipe is arranged in parallel with the outer surface of a large-diameter pipe by soldering. However, in this composite heat transfer tube, since the tubes having a circular cross section are joined to each other, the mutual contact surfaces are in line contact, and the heat exchange between the tubes is not effective. Further, since more than half of the entire circumference of the small-diameter pipe is covered with solder having poor heat conductivity, heat exchange between the pipes is further inhibited. In addition, the work process of joining and joining the pipes is very complicated and inefficient, consumes a large amount of solder, and unnecessarily increases the cost. (For example, see Patent Document 2).
[0004]
Furthermore, in order to increase the reliability of soldering, it is necessary to degrease the tube, apply a flux, remove the flux after soldering, and the like, which requires many work steps and is more complicated. In addition, since the tubular portion is soldered, it is easy to form a place where no solder is attached, a gap is formed between the large-diameter pipe and the small-diameter pipe, and the heat transfer performance is further reduced. Further, when the large-diameter pipe and / or the small-diameter pipe is formed of a copper pipe, a brittle Cu-Sn intermetallic compound is formed with the passage of time in the soldered portion, and a heat exchanger or the like in which a composite heat transfer tube is incorporated. Due to vibration or the like, the joint is easily detached, and the heat transfer performance deteriorates with time. Furthermore, since it is for a heat exchanger tube, moisture easily adheres, a local battery is formed due to a potential difference between copper and solder, and it is easily corroded, and a refrigerant may leak during use. Furthermore, when disposed and placed outdoors, rainwater elutes Pb ions harmful to the human body from the solder and contaminates the water source and surrounding environment. Furthermore, when recycling large diameter pipes and / or small diameter pipes to recycle Cu, it is difficult to separate the solder from the copper pipes, and Pb and Sn are mixed into Cu, and Cu can be recycled. Did not.
[0005]
As a specific example of a composite heat transfer tube that solves the above-described problem, as shown in FIG. 17, a small-diameter tube 103 is arranged in a groove 104 formed along the tube axis direction of a large-diameter tube 102, and its outer periphery is formed. There has been proposed a composite heat transfer tube 101 in which a resin layer 105 having closed cells with a low foaming ratio is coated and integrated (for example, see Patent Document 1).
[0006]
As shown in FIG. 18 (b), a hard small-diameter tube 123 is formed in a groove 124 formed in at least a part of an outer surface of a soft or light-soft large-diameter tube 122 except for both ends in parallel with the tube axis direction. Is proposed. Although not shown, as a method of forming a groove on the outer surface of the large-diameter pipe, a small indenter having a circular cross section coinciding with the groove cross section is arranged (fixed) in a part of the drawing part bearing and approach of the drawing die. There is a method of drawing out a large-diameter tube with this drawing die. Instead of the drawing method, a method in which a mandrel or a floating core is inserted into a large-diameter pipe and drawn out, or a method by roll forming is also known. Further, it is also known to use a drawing die or a roll as a method of tying and tightening a small-diameter pipe to a large-diameter pipe. (For example, see Patent Document 2).
[0007]
Also, as shown in FIG. 18A, a copper small-diameter tube 113 is fixed to a groove 114 formed in at least a part of the outer surface of the large-diameter tube 112 made of copper except for both end portions in parallel with the tube axis direction. The proposed composite heat transfer tube 111 has been proposed. The method for fixing the small-diameter pipe to the large-diameter pipe includes: (1) connecting the small-diameter pipe 113 to the large-diameter pipe 112 via a bonding layer 116 made of a brazing material, an adhesive, an eutectic insert member, a metal sealing material, or the like. There is a joining method, or (2) a method in which a small-diameter pipe is press-fitted into a groove of a large-diameter pipe, and then the large-diameter pipe is rolled to fit the small-diameter pipe. (It becomes the same as (b).) Further, as a method of forming a groove on the outer surface of a large-diameter pipe, it is known to use a double forming roller. (For example, see Patent Document 3).
[0008]
As shown in FIG. 19, two copper-made large-diameter pipes 132 are formed in a part of the outer surface excluding both ends and extend in parallel to the pipe axis direction. A heat exchanger 131 to which small-diameter pipes 133 and 133 are fixed has been proposed. The formation of the grooves 134 and 134 in the large-diameter tube 132 and the integration of the small-diameter tubes 133 and 133 in the grooves 134 and 134 are performed by drawing. Since the grooves 134, 134 of the large-diameter tube 132 are formed by a drawing process, in order not to form the grooves 134, 134 at both ends of the large-diameter tube 132, the both ends are reduced in diameter over a certain length. Therefore, at both ends of the large-diameter tube 132, reduced-diameter portions 132a and 132a whose outer diameters are smaller than those of the large-diameter tube 132 before processing are provided. Also, CO is supplied to the small diameter pipes 133 and 133. ₂ As an example used in a heat pump type heat exchanger that circulates water through a large-diameter tube 132 through a refrigerant, a configuration in which a composite heat transfer tube 131 is spirally wound is illustrated. (For example, see Patent Document 4).
[0009]
[Patent Document 1]
Japanese Utility Model Publication No. 55-159975 (page 1)
[Patent Document 2]
JP-A-57-90563 (pages 1 to 3, FIGS. 1 to 11)
[Patent Document 3]
JP-A-2000-283664 (paragraph numbers [0007] to [0031], FIGS. 3 to 10)
[Patent Document 4]
JP-A-2003-14383 (paragraph numbers [0025] to [0027], FIG. 4)
[0010]
[Problems to be solved by the invention]
However, in the composite heat transfer tube proposed in Patent Literature 1, the process of covering and integrating the foamed resin layer having closed cells with a low foaming rate is complicated, resulting in poor productivity. In addition, foamed resin generally tends to deteriorate with time due to changes in temperature and humidity. Due to the deterioration of the foamed resin, the contact state between the large-diameter pipe and the small-diameter pipe deteriorates, and the heat transfer performance and pressure resistance deteriorate with time. Further, since the composite heat transfer tube is covered with the foamed resin, the cross-sectional area of the cross section orthogonal to the tube axis of the composite heat transfer tube becomes large, and it is difficult to install the composite heat transfer tube in a small space, and a device such as a refrigerator using the composite heat transfer tube becomes large.
[0011]
Further, in the composite heat transfer tube proposed in Patent Document 2, a large-diameter tube is pulled out with a die in which a small indenter having a groove cross section is arranged to form a groove in a tube axial direction on the outer surface of the large-diameter tube. I have. Therefore, since the material of the large-diameter pipe forming the groove is soft or light-soft, and the drawing is performed by emptying (there is no plug inside the pipe), the cross-sectional shape of the formed groove becomes V-shaped. , It is difficult to form a C-shaped or U-shaped groove, and it is difficult to tighten and tighten the small-diameter pipe by reducing the gap with the large-diameter pipe by subsequent roll processing. It is difficult to improve strength. Further, in this method, a groove is formed in the entire length of the large-diameter pipe, and it is difficult to form a portion without a groove, and the problem of expansion described later remains. Further, since the contact area between the drawing die and the large-diameter pipe to be processed is large, the frictional force due to the drawing increases. Due to this frictional force, the pulling force of the large-diameter pipe increases, but the material of the large-diameter pipe is soft or light-soft, and the mechanical strength is small, so that the large-diameter pipe tends to seize or break during drawing. There is also a problem.
[0012]
Also, when the composite heat transfer tube is incorporated into a heat exchanger, the composite heat transfer tube is often subjected to a bending process. At this time, the small-diameter tube is easily detached from the V-shaped cross-section, and the bending processability is poor. Furthermore, even if roll formation is used to form the groove, since there is no plug inside the tube, the groove tends to have a V-shaped cross section, and it is difficult to form a C-shaped or U-shaped groove.
[0013]
In the composite heat transfer tube, the groove is formed over the entire length of the large-diameter tube, and when the composite heat transfer tube is incorporated in the heat exchanger, the end of the tube is expanded to braze the other tube. Is attached. Therefore, when brazing the pipe end, it is necessary to remove the small-diameter pipe once embedded from the groove of the large-diameter pipe, and it is difficult for the cross-section to become a perfect circle even when the pipe is expanded. Takes a long time to correct, and productivity is poor.
[0014]
Further, in the composite heat transfer tube manufactured by the fixing method of (1) proposed in Patent Document 3, the bonding layer made of brazing material or the like is easily deteriorated with time, and the large diameter is caused by vibration of equipment such as a refrigerator. The small diameter tube is easily detached from the tube, and the heat transfer performance and the pressure resistance deteriorate with time. Further, it is difficult to separate the joining layer (joining material) from the large-diameter pipe and the small-diameter pipe made of copper. For this reason, even if the composite heat transfer tube is melted and copper is recycled, the bonding material is mixed with copper, and recycling is difficult. In the composite heat transfer tube manufactured by the fixing method (2), since the groove is formed by two rollers, the cross-sectional shape of the groove becomes V-shaped. It is difficult to fix the small-diameter pipe without a gap inside, and the heat transfer performance and bending workability are not sufficient.
[0015]
Further, a common problem of the composite heat transfer tubes proposed in Patent Documents 1 to 3 is that heat exchange is performed by combining one large-diameter tube and one small-diameter tube, and the heat transfer area is insufficient. In order to increase the exchange capacity, it is necessary to take measures such as increasing the length of the heat transfer tube and providing a plurality of contact portions between the large-diameter tube and the small-diameter tube in parallel. And weight reduction are difficult.
[0016]
In addition, the heat transfer capacity of the composite heat transfer tube proposed in Patent Document 4 can be increased because two small-diameter tubes are fitted. Due to the necessity of connecting to another copper tube having an outer diameter, it is necessary to make the end of the reduced diameter portion have a certain outer diameter or more. For this purpose, it is necessary to use a raw tube having a large outer diameter. In that case, however, the cross-sectional area of the large-diameter tube where the small-diameter tube is fitted increases. Then, the flow rate of the heat medium flowing through the large-diameter pipe in the fitting portion decreases, and the heat transfer coefficient in this portion decreases. In addition, since the outer diameter of the fitting portion cannot be made smaller than a certain value, it is disadvantageous for downsizing the composite heat transfer tube. When the large-diameter pipe is long, the diameter reduction processing is complicated. When the reduced diameter portion is expanded to be brazed to another tube, the expansion ratio increases, and cracks and workability are likely to occur. Furthermore, since the cross-sectional area of the large-diameter tube changes at the position where the large-diameter tube moves from the reduced-diameter portion to the portion where the groove is formed, when water flows inside the large-diameter tube, the flow velocity changes near this position. , It is easy to cause scale accumulation and corrosion.
[0017]
Therefore, the present invention has been conceived to solve such a problem, and its object is to excel in heat transfer performance, bending workability, pressure resistance and productivity, and to further reduce the size of equipment used. An object of the present invention is to provide a composite heat transfer tube that can be reduced in weight and weight, and a method for manufacturing the same.
[0018]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 provides a large-diameter pipe having three or four grooves formed in at least a part of an outer surface excluding both ends in parallel with a pipe axis direction. A composite heat transfer tube having a diameter smaller than the diameter of the large-diameter tube and having three or four small-diameter tubes fitted into the three or four groove portions, respectively. The surface of the adjacent groove portion is configured as a composite heat transfer tube having an arc equal to the arc of the small diameter tube in contact with the surface.
[0019]
In the above configuration, since the surface of the groove has an arc equal to the arc of the small-diameter pipe in contact with the surface, the small-diameter pipe is in close contact with the surface of the groove, and the area of the contact portion between the large-diameter pipe and the small-diameter pipe (heat transfer area) As the area increases, the large-diameter pipe and the small-diameter pipe are firmly fitted, and the small-diameter pipe is prevented from coming off (falling out) from the groove.
[0020]
The outer diameter at both ends of the large-diameter pipe is the same as or larger than the outer diameter of the large-diameter pipe in the portion where the small-diameter pipe is fitted, and the small-diameter pipe has An outer diameter at both ends is the same as or larger than the outer diameter of the small-diameter tube in the other portions.
[0021]
In the above configuration, the outer diameter of both ends of the large-diameter tube is equal to or larger than the outer diameter of the large-diameter tube in the portion where the small-diameter tube is fitted, so that the composite heat transfer tube is incorporated into the heat exchanger. Therefore, it is not necessary to increase the outer diameter of the large-diameter tube at the portion where the small-diameter tube is fitted as in the conventional composite heat transfer tube, and the flow rate of the heat medium flowing in the large-diameter tube at the fitting portion does not decrease. . Further, since the outer diameter of the large-diameter tube does not increase at the fitting portion, the composite heat transfer tube is reduced in size. Further, by expanding both ends of the large-diameter pipe, it is easy to join the large-diameter pipe to another pipe when incorporating the large-diameter pipe into the heat exchanger.
[0022]
According to a third aspect of the present invention, the large-diameter pipe has a thickness t at a groove bottom portion of the groove portion fitted with the small-diameter tube, and a thickness T at a portion not fitted with the small-diameter tube. In this case, the composite heat transfer tube has a value of t / T of 0.3 to 0.7.
[0023]
In the above configuration, by setting the value of t / T within a predetermined range, it becomes easy to fit the small-diameter pipe to the large-diameter pipe, and it is difficult to form a gap between the large-diameter pipe and the small-diameter pipe. The groove bottom has a stress that can withstand the internal pressure of the large-diameter pipe, and the fitted small-diameter pipe is prevented from being pushed out of the large-diameter pipe. Further, the heat transfer performance between the large-diameter pipe and the small-diameter pipe is improved, the bending workability can be improved, and the arc of the surface of the groove of the large-diameter pipe is made equal to the arc of the small-diameter pipe. Can be formed.
[0024]
The arc of the surface of the groove adjacent to the small-diameter pipe may be an apparent contact length between the small-diameter pipe and the large-diameter pipe in a cross section orthogonal to the pipe axis of the composite heat transfer pipe. In addition, a composite heat transfer tube that is 55% or more of the entire circumference of the small-diameter tube is configured.
[0025]
In the above configuration, by setting the apparent contact length between the small-diameter pipe and the large-diameter pipe in the cross section orthogonal to the pipe axis of the composite heat transfer pipe to a predetermined length or more, the small-diameter pipe adheres to the surface of the groove, and the large-diameter pipe The contact area (heat transfer area) between the small-diameter pipe and the large-diameter pipe is increased, and the large-diameter pipe and the small-diameter pipe are firmly fitted to each other, thereby preventing the small-diameter pipe from coming off (falling out).
[0026]
According to a fifth aspect of the present invention, the three or four small-diameter pipes are fitted into three or four groove portions arranged at equal intervals in a cross section orthogonal to the pipe axis of the large-diameter pipe. This is configured as a combined heat transfer tube.
[0027]
In the above configuration, the heat transfer efficiency between the large-diameter pipe and the small-diameter pipe is improved by disposing the small-diameter pipes at equal intervals on the circumference of the large-diameter pipe in a cross section orthogonal to the pipe axis of the large-diameter pipe. At the same time, the workability of forming a groove for accommodating the small-diameter pipe in the large-diameter pipe and rolling fitting the small-diameter pipe into the groove is improved.
[0028]
According to a sixth aspect of the present invention, the large-diameter tube is configured as a composite heat transfer tube having a groove or a spiral groove formed in the inner surface thereof, the groove being parallel to the tube axis direction.
[0029]
In the above configuration, the parallel groove or the spiral groove increases the heat transfer area in the large-diameter tube, and the groove stirs the heat medium to improve the heat transfer performance.
[0030]
In the invention according to claim 7, three or four of the small-diameter pipes are fitted to the large-diameter pipe via a resin at least at a part of the surface of the three or four groove portions. It is configured as a composite heat transfer tube.
[0031]
In the above configuration, by fitting the large-diameter pipe and the small-diameter pipe via the resin, the resin is also filled in the minute gap formed on the surface where the large-diameter pipe and the small-diameter pipe are in contact with each other. By eliminating air with low thermal conductivity, the degree of close contact between the large-diameter pipe and the small-diameter pipe is further increased, the heat transfer area between the large-diameter pipe and the small-diameter pipe is further increased, and the fitting force of the small-diameter pipe to the large-diameter pipe is improved. Further increase.
[0032]
The invention according to claim 8 is configured such that at least one of the large-diameter pipe and the small-diameter pipe is a composite heat transfer pipe that is a copper pipe or a copper alloy pipe made of oxygen-free copper or phosphorus-deoxidized copper.
[0033]
In the above configuration, at least one of the large-diameter tube and the small-diameter tube has thermal conductivity, corrosion resistance, plastic workability (fitting, bending, and the like) by using a copper tube or a copper alloy tube made of oxygen-free copper or phosphorus deoxidized copper. As a result, the pressure resistance is improved, and the solderability at the time of assembling into the heat exchanger is improved.
[0034]
According to a ninth or tenth aspect of the present invention, the large-diameter pipe into which the three or four small-diameter pipes are fitted forms a spirally or spirally wound composite portion. It is configured as a heat tube.
[0035]
In the above-described configuration, the large-diameter tube fitted with the small-diameter tube forms a spiral or spiral winding portion, thereby increasing the length of the composite heat transfer tube that can be stored in the same volume, As a result, the heat transfer area increases, and the size of the heat exchanger can be reduced. Further, the stability of the composite heat transfer tube when installed in the heat exchanger is improved.
[0036]
According to an eleventh aspect of the present invention, the cross section of the large diameter pipe orthogonal to the pipe axis is configured as a composite heat transfer pipe having a non-circular cross section at a portion fitted with the small diameter pipe.
[0037]
In the above configuration, since the cross-sectional shape of the large-diameter pipe is non-circular, the height of the winding portion is reduced in the spiral winding portion having the same number of steps, or the spiral winding having the same number of turns. In the winding part, the outer diameter of the winding part becomes small.
[0038]
According to a twelfth aspect of the present invention, there is provided a composite transmission comprising a large-diameter pipe and three or four small-diameter pipes fitted on the outer surface of the large-diameter pipe in parallel with the pipe axis direction of the large-diameter pipe. A method for manufacturing a heat pipe, wherein a pin is pressed against an outer surface of the large-diameter pipe except for both ends thereof, and the pin is fixed to move the large-diameter pipe in parallel with the pipe axis direction. Forming a groove extending in the pipe axis direction at three or four locations on the outer surface of the large diameter pipe by fixing the diameter pipe and moving the pins in parallel with the pipe axis direction of the large diameter pipe; A step, an annealing step of annealing the large-diameter pipe in which the groove is formed, and placing three or four small-diameter pipes in three or four of the grooves, and rolling by a rolling roll into the groove. A rolling fitting step of embedding the small diameter pipe and fitting the annealed large diameter pipe and the small diameter pipe. Those configured as a production method of a composite heat transfer tube.
[0039]
In the above configuration, by forming the groove using a pin, only a predetermined portion of the large-diameter pipe is depressed inward to form a groove, and the edge of the formed groove is viewed in a cross section orthogonal to the pipe axis. A projection having a triangular cross-section is formed (in the conventional processing by rolling and drawing, the entire surface of the groove contacts the dies and rolls, so the projection is not formed). The projection falls down so as to enclose the small-diameter tube, and effectively acts to increase the fitting strength of the small-diameter tube. Other parts of the large diameter tube do not deform. Further, by annealing the large-diameter pipe having the groove formed therein, the large-diameter pipe and the small-diameter pipe are easily fitted, and the small-diameter pipe is not deformed. In addition, the bending property of the composite heat transfer tube is improved. In addition, the small-diameter pipe is firmly fixed in the groove of the large-diameter pipe by rolling-fitting with the rolling roll.
[0040]
The invention according to claim 13 is that at least one of the large-diameter pipe and the small-diameter pipe is a copper pipe or a copper alloy pipe made of oxygen-free copper or phosphorous deoxidized copper, and the large-diameter pipe has an outer surface. The 0.2% proof stress in the tube axis direction before forming the groove is 200 to 370 N / mm. ² Wherein the small-diameter pipe has a 0.2% proof stress of 200 N / mm in the pipe axis direction. ² This is configured as a method for manufacturing a composite heat transfer tube as described above.
[0041]
In the above configuration, by using a large-diameter pipe having a predetermined strength, the efficiency of forming a groove in the large-diameter pipe is improved, and breakage of a pin for forming the groove is suppressed. In addition, by using a small-diameter pipe having a predetermined strength, the small-diameter pipe is prevented from being deformed or flawed when the small-diameter pipe is fitted into the groove, and a gap between the large-diameter pipe and the small-diameter pipe is reduced. Further, it is possible to suppress an increase in pressure loss of the heat medium in the tube due to the deformation of the small-diameter tube.
[0042]
The invention according to claim 14 is a winding step of winding the large-diameter pipe fitted with the small-diameter pipe at a predetermined radius after the rolling fitting step, the large-diameter pipe and / or the small-diameter pipe. The present invention is configured as a method for manufacturing a composite heat transfer tube that performs at least one of a tube expansion step of expanding an end portion and an annealing step.
[0043]
In the above configuration, the winding step increases the heat transfer area as the composite heat transfer tube and reduces the space occupied by the composite heat transfer tube in the heat exchanger. Further, the stability of the composite heat transfer tube when installed in the heat exchanger is improved. In addition, the tube expansion step facilitates joining of the composite heat transfer tube with another tube when the tube is incorporated into a heat exchanger. Furthermore, the annealing step improves the bending workability of the composite heat transfer tube, and facilitates incorporation into a heat exchanger.
[0044]
An invention according to claim 15 is a composite transmission comprising a large-diameter pipe and three or four small-diameter pipes fitted on the outer surface of the large-diameter pipe in parallel with the pipe axis direction of the large-diameter pipe. A method for manufacturing a heat pipe, wherein a pin is pressed against an outer surface of the large-diameter pipe except for both ends thereof, and the pin is fixed to move the large-diameter pipe in parallel with the pipe axis direction. Forming a groove extending in the pipe axis direction at three or four locations on the outer surface of the large diameter pipe by fixing the diameter pipe and moving the pins in parallel with the pipe axis direction of the large diameter pipe; A step of annealing the large-diameter pipe having the groove formed therein, and applying a resin to at least a part of the surface of the three or four grooves, or forming three or four small-diameter pipes. A resin is applied to at least a part of a portion of the outer surface that is to be fitted with the annealed large diameter pipe. A grease application step, three or four small-diameter tubes are placed in the three or four grooves, and the small-diameter tubes are buried in the grooves by rolling with a rolling roll, and the annealed via the resin. A rolling fitting step of fitting the large-diameter pipe and the small-diameter pipe to each other, and heating the roll-fitted composite heat transfer tube to a curing temperature of the resin, heating the resin for a predetermined time, and curing the resin. And a step of manufacturing the composite heat transfer tube.
[0045]
The invention according to claim 16 is that at least one of the large-diameter pipe and the small-diameter pipe is a copper pipe or a copper alloy pipe made of oxygen-free copper or phosphorous deoxidized copper, and the pipe before forming the groove portion. A method for manufacturing a composite heat transfer tube in which the 0.2% proof stress of the large-diameter tube and the small-diameter tube is within a predetermined range, and the invention according to claim 17 further includes a winding step after the rolling fitting step. This is configured as a method for manufacturing a composite heat transfer tube that performs at least one of a pipe expansion step and an annealing step.
[0046]
In the above-described configuration, the resin is filled into the minute gaps formed on the contact surface between the large-diameter tube and the small-diameter tube by the resin application step and the resin curing step, and air having low thermal conductivity is eliminated from the contact surface. In addition, the degree of close contact between the large-diameter pipe and the small-diameter pipe is further increased, the heat transfer area between the large-diameter pipe and the small-diameter pipe is further increased, and the fitting force of the small-diameter pipe to the large-diameter pipe is further increased.
[0047]
In addition, by using a large-diameter pipe having a predetermined strength, the efficiency of forming a groove in the large-diameter pipe is improved, and breakage of a pin for forming the groove is suppressed. In addition, by using a small-diameter pipe having a predetermined strength, the small-diameter pipe is prevented from being deformed or flawed when the small-diameter pipe is fitted into the groove, and a gap between the large-diameter pipe and the small-diameter pipe is reduced. Further, it is possible to suppress an increase in pressure loss of the heat medium in the tube due to the deformation of the small-diameter tube. In addition, the winding step increases the heat transfer area of the composite heat transfer tube and reduces the space occupied by the composite heat transfer tube in the heat exchanger. Further, the stability of the composite heat transfer tube when installed in the heat exchanger is improved. In addition, the tube expansion step facilitates joining of the composite heat transfer tube with another tube when the tube is incorporated into a heat exchanger. Furthermore, the annealing step improves the bending workability of the composite heat transfer tube, and facilitates incorporation into a heat exchanger.
[0048]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A is a side view of a composite heat transfer tube including three small-diameter tubes, FIG. 1B is a partially cutaway perspective view showing an end of a groove, and FIG. 2 is a cross-sectional view taken along line XX of FIG. 3 is a cross-sectional view of another embodiment of FIG. 2, FIG. 4 is a cross-sectional view of another embodiment of FIG. 2, FIG. 5 is a cross-sectional view of a composite heat transfer tube having four small-diameter tubes, and FIG. FIG. 7 is a sectional view of another embodiment, FIG. 7 is a tube axis parallel sectional view schematically showing a groove forming step of forming grooves at four locations of a large diameter pipe, and FIG. 8 is a groove forming step of forming grooves in a large diameter pipe. FIGS. 9A and 9B are schematic cross-sectional views schematically showing the tube axis. FIG. 9A shows a case where four groove portions are fitted, FIG. 9B shows a case where four groove portions are fitted, and FIG. FIG. 10 is a tube axis orthogonal cross-sectional view schematically showing a rolling fitting process of fitting a small-diameter tube to a large-diameter tube, and FIG. If there are four, (b) In the case of three diameter tubes, FIG. 11 (a) is a partially enlarged sectional view of the groove before fitting in FIG. 10, (b) is a partially enlarged sectional view of the groove after fitting, and (c) is (b) FIG. 12 is an explanatory view schematically showing a configuration of a heat exchanger, FIG. 13 is a perspective view of a composite heat transfer tube having a spirally wound portion, and FIG. 13A is a cross-sectional view taken along the line C-C of FIG. 13, FIGS. 13B and 13C are partial cross-sectional views showing another embodiment of FIG. 13, and FIG. 15 is a composite transmission having a spirally wound part. FIG. 16A is a perspective view of a heat tube, FIG. 16A is a cross-sectional view taken along line DD of FIG. 15, and FIG. 16B is a partial cross-sectional view showing another embodiment of FIG.
[0049]
As shown in FIG. 1, a composite heat transfer tube 1 of the present invention includes a large-diameter pipe 2 having three grooves 4, 4, 4 formed on the outer surface thereof, and a groove 4, 4, 4 and three small-diameter tubes 3, 3, 3. Alternatively, a large-diameter pipe having four grooves and four small-diameter pipes fitted into the grooves of the large-diameter pipe are provided (not shown).
[0050]
(Structure of large diameter pipe)
The large-diameter pipe 2 has a larger outer diameter than the small-diameter pipe 3 described later, and even when three or four small-diameter pipes 3 are fitted to each other to form the composite heat transfer pipe 1, a CFC-based refrigerant and water It is sufficient that the inner diameter and the pressure resistance are sufficient to flow the fluid, and as an example, the outer diameter is preferably 4 to 30 mm, the thickness is 0.2 to 2.5 mm, and the length is preferably 100 mm or more. There is no particular limitation on the dimensions as long as the condition that the outer diameter is larger than that of the small diameter pipe is satisfied. Generally, it is determined in consideration of the relationship with the small-diameter tube size, the size, heat capacity, and workability of the heat exchanger in which the heat transfer tube of the present invention is incorporated, and there is no problem other than the above-mentioned size.
[0051]
Further, as a material of the large-diameter tube 2, copper or a copper alloy specified in JIS H3300 is preferable from the viewpoint of thermal conductivity and corrosion resistance. Even if not specified, the tube or the groove can be processed. If applicable. In addition to copper and copper alloy, aluminum, aluminum alloy, stainless steel, and the like can also be used.
[0052]
The large-diameter pipe 2 can be subjected to plastic processing such as groove processing on the outer surface of the pipe, fitting of each small-diameter pipe 3, spiral or spiral winding. It is desirable to have mechanical properties that do not occur such as detachment. In addition, since the bending process is performed when the composite heat transfer tube 1 is incorporated in a heat exchanger, it is desirable that the composite heat transfer tube 1 has mechanical properties such that the bending process does not cause cracking or detachment of the small-diameter tube.
[0053]
Further, since it is joined to another tube by brazing, soldering, or the like to be incorporated in the heat exchanger, it is desirable that the brazing property and the soldering property be excellent.
[0054]
The large diameter pipe 2 may be a seamless pipe manufactured by rolling and drawing an extruded raw pipe, or a welded pipe manufactured by welding a width-direction end face of a strip having a predetermined width. May be used.
[0055]
Further, usually, a smooth tube having a smooth inner surface is often used as the large-diameter tube 2. However, when it is desired to agitate the heat medium in the tube, to provide a swirling flow, or to increase the heat transfer area in the tube. If desired, an inner grooved tube having a groove parallel to the tube axis or a spiral groove (not shown) formed on at least a part of the inner surface of the tube may be used. In addition, the groove processing in the large-diameter pipe 2 is performed by a rolling method, a rolling method (using a rolling roll instead of a rolling ball), and a groove (a narrow plate-shaped sheet) formed with a rolling roll. And welding the ends.
[0056]
(Structure of small diameter pipe)
Three or four small-diameter tubes 3 are fitted to the large-diameter tube 2 and are formed in such a size that a required amount of heat medium can flow through the inside of the large-diameter tube 2. When the pressure of the heat medium flowing through the inside of the small-diameter pipe is large, a thickness that can withstand the operating pressure is required. As an example, the outer diameter is preferably 1 to 8 mm, the thickness is preferably 0.2 to 5 mm, and the length is preferably 100 mm or more. In addition, there is no problem even outside the above dimensions as long as the condition that the outer diameter is smaller than that of the large diameter pipe is satisfied.
[0057]
The material of the small-diameter tube 3 is preferably copper or a copper alloy specified in JIS 3300 in terms of thermal conductivity and corrosion resistance. If not specified, the material can be processed into a tube, and any material that can be bent can be used. . In addition to copper and copper alloys, aluminum, aluminum alloys, stainless steels, and the like can also be used. In addition, the workability of the small-diameter tube 3 is such that the composite heat transfer tube 1 is provided with a mechanical property that does not break due to winding and does not come off from the large-diameter tube 2 because it is wound in a spiral or spiral shape. Is desirable. Further, since the bending process is performed when the composite heat transfer tube 1 is incorporated into a heat exchanger, it is desirable that the composite heat transfer tube 1 has mechanical properties such that it does not break even in the bending process and does not detach from the large-diameter tube 2.
[0058]
Since it is joined to another tube by brazing, soldering or the like to be incorporated in the heat exchanger, it is desirable that the brazing property and the soldering property be excellent.
[0059]
The small-diameter pipe 3 has a small cross-sectional area, but is often operated with a higher internal pressure than the large-diameter pipe 2 because it is often desired to increase the flow rate of the heat medium flowing inside. For this reason, the thickness of the tube relative to the outer diameter of the tube is often increased, and in general, a seamless tube manufactured by rolling and drawing an extruded raw tube is often used. The wall thickness of the pipe may be determined from the pressure resistance calculated based on the operating pressure of the heat exchanger. If the pressure resistance satisfies the required value, a welded pipe may be used.
[0060]
A smooth tube whose inner surface is smooth is often used.However, when it is desired to agitate the heat medium in the tube, to provide a swirling flow, or to increase the heat transfer area in the tube, at least the inner surface of the tube is used. An inner grooved pipe in which a spiral or a groove parallel to the pipe axis direction is partially formed may be used.
[0061]
(Composition of composite heat transfer tube)
As shown in FIGS. 1 to 6, the composite heat transfer tube 1 has three or four tubes formed parallel to at least a part of the outer surface of the large-diameter tube 2 except for both ends 2 a and 2 a along the tube axis direction. Three or four small-diameter tubes 3 are fitted into the four groove portions 4 in close contact with each other, and the surface 4A of each groove portion 4 adjacent to each small-diameter tube 3 is in contact with each surface 4A. 3 has an arc equal to 3A.
[0062]
The length of the composite section B in which each small-diameter pipe 3 is fitted into each groove 4 of the large-diameter pipe 2 is not particularly limited, but is preferably 100 mm or more. In a portion A other than the composite section B, the large-diameter pipe 2 and the small-diameter pipes 3 are separated from each other, and both ends 2a and 3a of the respective pipes are connected to necessary portions of the heat exchanger 20. (See FIG. 12). When both ends 2a of the separated large-diameter tube 2 and / or both ends 3a of each small-diameter tube 3 are expanded (expanded portion) by a predetermined length for the connection, brazing is performed. It is suitable. As shown in FIGS. 13 and 15, spiral or spiral winding portions 31 k and 61 k may be formed in the composite section B.
[0063]
Further, it is preferable that the length of the arc (the arc 3A of the fitted small diameter pipe 3) in the cross section orthogonal to the pipe axis of the surface 4A of each groove 4 is 55% or more of the entire circumference of each small diameter pipe 3. . As a result, 55% or more of the outer surface of each small-diameter tube 3 is covered by the surface 4A of each groove 4. Further, it is more preferably at least 70%. When the length of the arc of each surface 4A (the arc 3A of each small-diameter tube 3) is less than 55% of the entire circumference of each small-diameter tube 3, the composite heat transfer tube 1 is straight and bent, for example. When used in a spiral or spiral shape, the small-diameter tube 3 may come off (or come off) from the large-diameter tube 2 (each groove 4), or the heat between the large-diameter tube 2 and each small-diameter tube 3 Replacement is likely to decrease. The length (%) of the arc is obtained as follows. The section where each small diameter pipe 3 is fitted is observed in a section orthogonal to the pipe axis, and the circumferential angle of each small diameter pipe 3 is measured with respect to the section where each small diameter pipe 3 and large diameter pipe 2 are in apparent contact. I do. [Measured circumference angle (°) / 360 (°)] × 100 is the value to be obtained. Usually, an average value is obtained for three or four small diameter tubes 3 in one cross section, the average value is obtained for three or more cross sections, and a value obtained by further averaging the average values is determined. In addition, “apparent” means that it should essentially be in contact (the section is surrounded by the large-diameter tube 2), and includes a part that is not in contact on a microscope scale.
[0064]
Further, at both ends of the composite section B of the large-diameter pipe 2 and each small-diameter pipe 3, each groove 4 formed in the large-diameter pipe 2 becomes shallow at an angle θ of about 30 ° with the pipe axis direction. By doing so, each small-diameter tube 3 can be separated (separated) from the large-diameter tube 2 without applying excessive force.
[0065]
In addition, the fitting form may be such that each small-diameter tube 3 is embedded in the outer surface of the large-diameter tube 2 in parallel to the tube axis direction. As described later, the method of forming such a fitting form is such that the outer surface of the large-diameter tube 2 is substantially equal to the outer diameter of each small-diameter tube 3 in parallel to the tube axis direction, and the depth is equal to the above-mentioned depth. Each groove 4 having a predetermined depth necessary to form the surface 4A is formed, each small-diameter tube 3 is fitted into each groove 4, and then the projections 4a, 4a formed in each groove 4 of the large-diameter tube 2 are formed. It is formed by covering each small diameter pipe 3 by a method such as rolling and fixing each small diameter pipe 3 to the large diameter pipe 2. Then, a contact state in which each small-diameter tube 3 is in close contact with the large-diameter tube 2 is formed (see FIG. 11).
[0066]
However, in such a fitting form, in each groove 4, a fine gap remains between the large-diameter pipe 2 and each small-diameter pipe 3 in the pipe axis orthogonal direction and the pipe axis direction. Since the area of the contact portion with the small diameter pipes 3 is large, sufficient heat transfer performance can be exhibited.
[0067]
Further, in the composite heat transfer tube of the present invention, as shown in FIG. 2 and FIG. 5, the positions of three or four small-diameter tubes with respect to the large-diameter tube when viewed in a cross section orthogonal to the pipe axis of the composite heat transfer tube are as follows. It is preferable that three or four small-diameter pipes 3 are provided at equal intervals on the circumference of the large-diameter pipe 2 in a cross section orthogonal to the pipe axis of the large-diameter pipe 2. The composite heat transfer tube 1 having such a configuration has a high heat transfer efficiency and is most preferably used. Further, the processing of each groove 4 for accommodating each small diameter tube 3 described later, and the processing of each small diameter tube 3 into each groove 4 are performed. Is the easiest to fit. The composite heat transfer tube 1 is suitably used particularly when the flow rate of the heat medium flowing through the large-diameter tube 2 is large.
[0068]
The positions of the three or four small-diameter tubes 3 are not limited to only FIGS. 2 and 5, but can be located at various positions. For example, when the flow rate of the heat medium flowing in the large-diameter tube 2 is small, three or four small-diameter tubes are located at positions separated by 60 ° in the cross section orthogonal to the tube axis of the large-diameter tube 2 in FIGS. There is a pipe 3 or a small-diameter pipe in which the arrangement of the small-diameter pipes is not uniform, in which three small-diameter pipes 3 exist at positions separated by 90 ° in a cross section orthogonal to the pipe axis of the large-diameter pipe 2 in FIG. Sometimes. However, for processing of each groove 4 for accommodating each small-diameter tube 3, fitting of each small-diameter tube 3 to each groove 4, and bending at the time of incorporating the composite heat transfer tube 1 into a heat exchanger, A tube corresponding to the arrangement of each small diameter tube 3 is required.
[0069]
The composite heat transfer tube in which three or four small-diameter tubes are fitted to a large-diameter tube in this way has a higher degree of difficulty in groove processing, fitting, and the like than a tube in which one or two small-diameter tubes are fitted. Is higher, but the effect is more than expected on the improvement of heat transfer performance due to the increase in the number of small diameter tubes (increase in contact area) and the miniaturization of heat exchangers manufactured using this composite heat transfer tube. It is something that can be done. Significant improvement in heat transfer performance is achieved by the following mechanism.
[0070]
(1) The large-diameter pipe has a shape in which three or four ribs are formed in the large-diameter pipe due to formation of a groove extending in the pipe axis direction, and one or two ribs are formed. In comparison, the effect of stirring the heat medium flowing in the large-diameter tube is significantly increased. For this reason, the heat transfer performance in a large-diameter pipe is greatly improved.
[0071]
(2) Since three or four small-diameter tubes are fitted, the cross-sectional area of the large-diameter tube in a cross section orthogonal to the tube axis is small (for example, FIGS. 2 to 6), and the heat having the same mass per unit time is obtained. When the medium flows into the large-diameter pipe, the flow velocity increases, so that the heat transfer performance in the large-diameter pipe is greatly improved.
[0072]
(3) When the composite heat transfer tube is bent, the contact state between the large-diameter tube and the small-diameter tube changes at the bent portion, and the heat transfer performance is affected. However, the number of small-diameter tubes must be three or four. Thereby, the change in the contact state is averaged, and the influence on the heat transfer performance is reduced.
[0073]
(4) Since three or four small-diameter pipes are fitted, the contact area between the large-diameter pipe and the small-diameter pipe increases, and the amount of heat transfer between the large-diameter pipe and the small-diameter pipe increases.
In addition, since the heat transfer performance can be significantly improved in this way, the length of the composite heat transfer tube required to manufacture a heat exchanger having the same heat capacity can be shortened, thereby reducing the size of the heat exchanger. Weight reduction can be achieved.
[0074]
As shown in FIG. 13 to FIG. 16, after the small-diameter tube 3 is fitted to the large-diameter tube 2, the composite heat transfer tube 1 has an appropriate winding diameter and an appropriate spacing between the tubes in the winding height H direction. Thus, the winding portions 31k, 41k, 51k, and 61k may be formed in a spiral or spiral shape.
[0075]
(Helical winding)
As shown in FIGS. 13 and 14A, the minimum inner diameter ID of the winding of the winding portion 31 k is the outer diameter of the large-diameter pipe 2 and each small-diameter pipe 3, and the thickness of the large-diameter pipe 2 and each small-diameter pipe 3. Depends on the crystal grain size of the large-diameter tube 2 and each small-diameter tube 3 and the mechanical properties (tensile strength, proof stress, elongation, spring limit value, etc.) of the large-diameter tube 2 and each small-diameter tube 3. Assuming that the outer diameter a of the diameter pipe is a constant “a”, the minimum inner diameter ID of the winding portion 31k can be reduced to about 6 × a. Further, in order to reduce the height H of the winding portion 31k, after each small-diameter tube 3 is fitted to the large-diameter tube 2, annealing may be further performed.
[0076]
The distance p between the large-diameter pipes 2 of the winding portion 31k may be such that the large-diameter pipes are in contact with each other (p） 2 × a), or may be a state in which a gap is provided and no contact is made. In order to reduce the size of the wound portion 31k, it is preferable to reduce the interval p between the wound portions 31k and bring adjacent pipes into contact with each other, which is effective in reducing the size of the composite heat transfer tube 31. Further, as shown in FIG. 14C, when the outer shape of the large-diameter pipe 52 in the cross section orthogonal to the pipe axis is an ellipse or a flat circular shape (left-right diameter> up-down diameter), the height H of the winding portion 51k is further increased. It is possible to reduce.
[0077]
Although FIG. 14A shows an example of a single winding, in order to further improve the heat exchange capacity of the winding portion 31k, as shown in FIG. It is good also as composition wound only.
[0078]
(Swirled winding part)
As shown in FIGS. 15 and 16A, the maximum outer diameter OD and the minimum inner diameter ID of the winding of the winding portion 61k are the outer diameter of the large-diameter pipe 2 and each small-diameter pipe 3, the large-diameter pipe 2 and each small-diameter. Depends on the wall thickness of the tube 3, the crystal grain size of the large-diameter tube 2 and each small-diameter tube 3, and the mechanical properties (tensile strength, proof stress, elongation, spring limit value, etc.) of the large-diameter tube 2 and each small-diameter tube 3. However, for example, when the outer diameter a of the large diameter pipe is a constant “a”, the maximum outer diameter OD of the winding portion 61k can be increased to about 40 times a, and further, the minimum inner diameter ID Can be reduced to about 6 times a. Further, in order to reduce the height H of the winding portion 61k, annealing may be further performed after each small-diameter tube 3 is fitted to the large-diameter tube 2.
[0079]
The distance p between the large-diameter pipes 2 of the winding portion 61k may be such that the large-diameter pipes are in contact with each other (p ≒ 2 × a), or may be a state in which a gap is provided and the large-diameter pipes are not in contact. In order to reduce the size of the wound portion 61k, it is preferable to reduce the interval p between the wound portions 61k and bring adjacent pipes into contact with each other, which is effective in reducing the size of the composite heat transfer tube 61. Further, as shown in FIG. 16B, when the outer shape of the large-diameter pipe 72 in the cross section orthogonal to the pipe axis is an ellipse or a flat circular shape (right and left diameter <vertical diameter), the height H of the winding portion 71k is further increased. It is possible to reduce.
[0080]
FIGS. 15 and 16 (a) show an example in which two spiral winding portions 61k are formed and stacked in two layers, but the number of winding portions 61k may be one, or may be one. In order to further improve the heat exchange capacity of the portion 61k, three or more layers may be formed. In the case of two or more winding portions 61k, the transition portion 61i of each winding portion 61k may be continuously wound so that the next winding portion 61k overlaps in the vertical direction as shown in FIG. Then, the ends of the respective winding portions may be joined directly (by brazing or the like) or by using a connection pipe or the like so that the next winding portion has the same plane shape.
[0081]
In order to enhance the heat insulation of the fitting portion between the large-diameter tubes 2, 52, 72 and the small-diameter tubes 3, 53, 73, a fitting portion including the winding portions 31k, 41k, 51k, 61k, 71k is required. It may be covered with a heat-insulating resin or a heat-insulating material described later (not shown). The material of the resin may be selected according to the temperature of the heat medium flowing inside the large-diameter pipes 2, 52, 72 and the small-diameter pipes 3, 53, 73. CO on 53, 73 ₂ In order to warm the water of the large-diameter pipes 2, 52, and 72, a material having excellent heat resistance and not deteriorating over a long period of time may be selected.
[0082]
As shown in FIGS. 2 to 6, in the composite heat transfer tube 1 of the present invention, three or four small-diameter tubes 3 are provided with a resin 5 (see FIG. 2) on at least a part of the surface of the three or four groove portions 4. 11 (c)) is preferable. As described above, it is difficult to completely eliminate the minute gap between the large-diameter pipe 2 and the small-diameter pipe 3 in the groove 4. For this reason, if there is a minute gap, air is interposed and the heat conductivity is lower than that of metal and the heat transfer resistance is higher. Therefore, the resin 5 having higher heat conductivity than air is provided in the portion where air is interposed. . By providing the resin 5, the composite heat transfer tube 1 in which the heat transfer performance in each groove 4 is further improved is obtained.
[0083]
As a method of filling the resin into the minute gaps, the resin 5 in a flowing state (see FIG. 11C) is filled with three or four grooves 4 of the large diameter pipe 2 before fitting. Alternatively, after applying a required amount to the outer surface 3A of each of the three or four small-diameter pipes 3, and fitting the three or four small-diameter pipes 3 to the large-diameter pipe 2, a resin is applied. 5 may be cured (for example, heated).
[0084]
Further, the resin 5 (see FIG. 11 (c)) protruding from each of the three or four grooves 4 due to the fitting process does not contribute to the improvement of the heat transfer performance of the gap, and thus is removed before or after the resin 5 is cured. You may. If the resin 5 itself does not adversely affect the corrosion resistance and the like, it may be left as it is.
[0085]
Examples of the type of the resin 5 (see FIG. 11C) include polyethylene glycol (PEG) and organic-inorganic hybrid ceramics (organic modified silicate material, so-called ceramer, etc.). Organic-inorganic hybrid ceramics have both inorganic and organic properties because the inorganic portion is networked by being bound by an organic polymer or oligomer. Therefore, it is possible to follow the thermal expansion and contraction of the base material due to the temperature difference in the heat exchanger or the cooling / heating cycle while having a dense and excellent strength.
[0086]
These resins 5 (see FIG. 11C) can be used after being diluted to a desired concentration with an appropriate solvent such as water or an organic solvent. Although the resin 5 is not particularly limited to the above, it has fluidity at a temperature around room temperature, its curing temperature is 200 ° C. or less, and the corrosion resistance, the stress corrosion cracking resistance, the nest resistance of the large-diameter pipe 2 and each small-diameter pipe 3. Those that do not adversely affect corrosiveness are desirable. Further, in order to adjust the fluidity, heat transfer performance, expansion coefficient, etc. of the resin 5, a metal or alloy powder, a metal oxide powder, or the like of the same material as the large-diameter pipe 2 and / or each small-diameter pipe 3 is used. 5 may be added.
[0087]
Further, in the composite heat transfer tube of the present invention, as shown in FIGS. 2 to 6, the thickness of the groove bottom portion 4 b of the groove portion 4 in which the large diameter tube 2 is fitted with the small diameter tube 3 is t (FIG. 4, the average value of t1, t2, and t3 at t1, t2, and t3, and the average value of t1, t2, t3, and t4 at t1, t2, t3, and t4 in FIGS. The thickness of the unmatched portion is represented by T (T1 in FIGS. 2 to 4, T1, T2, T3, T4 or T1 in FIGS. 5 to 6, T1 or the average value of T1, T2, T3, T4 or T1). ), It is preferable that the value of t / T is 0.3 to 0.7.
[0088]
The value of t / T affects the ease of fitting the large-diameter pipe 2 and the small-diameter pipe 3 and the pressure resistance of the composite heat transfer tube 1 thus manufactured. If t / T is smaller than 0.3, the thickness t of the groove bottom portion 4b becomes thin and the small-diameter pipe 3 is easily fitted. However, the stress required to project the groove bottom portion 4b outward is Become smaller.
[0089]
Therefore, when pressure is applied to the inside of the large-diameter pipe 2, the small-diameter pipe 3 fitted in the groove 4 is pushed outward by the internal pressure acting in the pipe circumferential direction from the inside to the outside of the large-diameter pipe 2. And the pressure resistance of the composite heat transfer tube is reduced. If t / T is larger than 0.7, it is difficult to fit the small-diameter pipe 3 to the large-diameter pipe 2. Thereby, after fitting, a large gap is formed between the surface 4A of the groove 4 and the arc 3A of the small-diameter tube 3, and the heat transfer performance of the composite heat transfer tube 1 is likely to be reduced.
[0090]
The composite heat transfer tube 1 of the present invention is preferably made of a material in which at least one of the large-diameter tube 2 and the small-diameter tube 3 is a copper tube or a copper alloy tube made of oxygen-free copper or phosphorus-deoxidized copper.
[0091]
The characteristics required as a composite heat transfer tube are as follows: (1) The large-diameter tube and the small-diameter tube have excellent thermal conductivity of each tube, and can efficiently exchange heat between the heat medium flowing inside the large-diameter tube and the small-diameter tube; (2) The large-diameter pipe and the small-diameter pipe are excellent in corrosion resistance in various use atmospheres; (3) The large-diameter pipe and the small-diameter pipe are excellent in plastic workability such as fitting and bending; (5) The large-diameter pipe and the small-diameter pipe have a predetermined pressure resistance, and the like.
As the material of the large-diameter pipe and the small-diameter pipe satisfying these characteristics (1) to (5), alloy number C1101 specified in JIS H3300 widely used as a heat exchanger tube for a heat exchanger of an air conditioner, a large air conditioner or the like. Of oxygen-free copper, and any of alloy dephosphorized copper of C1201 and C1220 are preferred.
[0092]
Further, as the material for the composite heat transfer tube of the present invention, it is not necessary to limit to only the above-mentioned material, and when a pressure resistance is required in addition to the heat conductivity, copper or a copper alloy specified in JIS 3300, for example, A copper alloy not specified in JIS H3300 in which one or more selected from elements such as Fe, P, Ni, Co, Mn, Sn, Si, Mg, Ag, and Al are contained in a total of several percent or less in Cu. Can be used.
[0093]
In particular, when corrosion resistance and pressure resistance are required, Cu-Ni alloys such as alloy numbers C7060, C7100, and C7150 specified in JIS 3300, Ti or Ti alloy, stainless steel, and the like can be used. When weight reduction is required, it is also possible to select an aluminum or aluminum alloy having predetermined characteristics in consideration of characteristics such as corrosion resistance, strength, and workability.
[0094]
Further, as shown in FIG. 1, in the composite heat transfer tube of the present invention, it is preferable that the outer diameter of the large-diameter tube at both ends is the same as the outer diameter of the large-diameter tube in the portion where the small-diameter tube is fitted. . Here, the outer diameter of the large diameter pipe at the fitting portion is the outer diameter of the large diameter pipe measured without the groove. With such a configuration, the cross-sectional area of the large-diameter tube in the portion where the small-diameter tube is fitted is smaller than the end portions, and the flow rate of the heat medium flowing through this portion does not decrease. It is possible to improve. Further, it is possible to manufacture a composite heat transfer tube using a large-diameter tube having an outer diameter smaller than that of the composite heat transfer tube of Patent Document 4, which is also effective for downsizing the heat exchanger. Further, it is preferable that a large-diameter tube and / or a small-diameter tube have expanded portions of a predetermined length formed at both ends. When incorporating a composite heat transfer tube into a heat exchanger, it is necessary to join it with other tubes of the same outer diameter as the large diameter tube by brazing, soldering, etc. In this case, the end of the large diameter tube is required Expanding the tube by the length is convenient for joining (see FIG. 12). In addition, a generally used expansion jig may be used for expansion. Furthermore, the same applies to the case where the small-diameter tube is joined to another tube having the same outer diameter by brazing, soldering, or the like.
[0095]
Next, a method for manufacturing the composite heat transfer tube of the present invention will be described. The manufacturing method of the present invention includes a groove forming step, an annealing step, and a rolling fitting step.
(1) Groove forming step
As shown in FIGS. 7, 8 (a) and 8 (b), three or four pins 10 fixed by a fixing jig so that the processing tip 11 a protrudes inside the sleeve 15 at a predetermined position of the sleeve 15. Is pressed against the outer surface of the large-diameter tube 2 except for both ends, and the three or four pins 10 are fixed, and the large-diameter tube 2 is moved in parallel with the tube axis direction by, for example, a holding roll (not shown). Or by moving the pin 10 parallel to the tube axis direction of the large-diameter tube 2 while the large-diameter tube 2 is fixed (not shown), at three or four positions on the outer surface of the large-diameter tube 2. A groove 4 extending in the pipe axis direction is formed at a location.
[0096]
(pin)
The pin 10 includes a grooved portion 11 having a predetermined length and a grip portion 12 having a larger diameter. In addition, the groove processing portion tip 11a is processed into a hemispherical shape, and a predetermined radius is attached to the connecting portion 13 between the grip portion 12 and the groove processing portion 11 to alleviate destruction due to stress concentration (the shoulder portion 14 is also provided). Predetermined chamfers have been made). In addition, the outer diameter of the grooved portion tip 11a is often set to about ± 0 to 20% of the outer diameter of the small diameter pipe. This is because even if the outer diameter of the grooved portion tip 11a is larger than the outer diameter of the small diameter pipe, the outer diameter of the grooved portion 4 is elastically deformed after the grooved portion is processed. This is because it becomes smaller.
[0097]
Further, since the pin 10 is pressed against the large-diameter pipe 2 and the large-diameter pipe 2 or the pin 10 is moved in the pipe axis direction while the large-diameter pipe 2 is depressed by a predetermined depth, the groove 4 is formed. The pin 10 is required to be hardly deformed (having high mechanical strength), hard to be worn (excellent in wear resistance), not broken during processing of the groove 4 (excellent in impact resistance), and the like.
[0098]
From such a point, the material of the pin 10 is preferably a cemented carbide material. In particular, WC (tungsten carbide) having an average particle diameter of less than 1 micron has a long life and is desirable. In addition, when the pin portion is coated with a ceramic material such as SiC, SiN, AlN, or sialon or a coating such as amorphous carbon by a method such as CVD or PVD, the moldability (workability) of the groove 4 and the life of the pin 10 are reduced. Further improve.
[0099]
(Method of forming grooves)
The three or four pins 10 are pressed against three or four places of the large-diameter tube 2 where the groove 4 is to be formed, and the large-diameter tube 2 is depressed to a predetermined depth. When two or each pin 10 is moved by a predetermined length in the pipe axis direction, grooves can be formed at three or four positions at the same time. The number of the pins 10 is reduced to one or two, and the large-diameter pipe 2 or the pins 10 are moved in the pipe axis direction. First, a groove 4 having a predetermined length and a predetermined depth is formed in one place of the large-diameter pipe 2. Thereafter, the large-diameter pipe 2 may be rotated around the pipe axis, and second or more grooves may be formed at other positions by a similar method (not shown). Further, each of the grooves 4 having a desired depth may be formed by one movement or two or more movements by these methods.
[0100]
The pressing force of each pin 10 during the processing of each groove 4, the moving speed of each pin 10 or the large-diameter tube 2, and the number of times of movement are determined by the material and mechanical properties of the large-diameter tube 2, In consideration of the depth, only each groove 4 is formed in the large-diameter pipe 2, and the other part (other than each groove 4) of the large-diameter pipe 2 is not deformed. An appropriate condition may be selected so as to reduce the occurrence.
[0101]
Further, since the processing of each groove 4 is a strong processing, it is more suitable than various lubricating oils used for drawing and rolling of pipes in order to reduce generation of processing heat and generation of burrs and cutting chips on a processed part. It is desirable to select and use. If a blower is installed on the processing target and processing is performed while air blowing, chips generated and excess lubricating oil can be removed.
[0102]
(2) Annealing process
In a large diameter pipe having a groove formed on the outer surface, a processed portion (groove) is work-hardened. In this state, when a rolling fitting step described later shown in FIGS. 9, 10A and 10B is performed (when each small diameter pipe 3 is fitted into each groove 4 of the large diameter pipe 2), a large diameter Since the deformation resistance of the processed portion of the pipe 2 is large and the ductility is reduced, a gap is easily formed between the large-diameter pipe 2 and each small-diameter pipe 3 in each groove 4, and each small-diameter pipe 3 is deformed. It will be easier. In addition, when plastic working such as bending is performed on the composite heat transfer tube 1 in order to incorporate the manufactured composite heat transfer tube 1 into the heat exchanger, workability may be reduced. In order to avoid such a problem, the large-diameter pipe 2 after the groove forming step needs to be annealed by using an annealing apparatus (not shown) to be a soft material.
[0103]
When the material of the large-diameter pipe is oxygen-free copper or phosphorous deoxidized copper, the lubricating oil used in the groove forming step is degreased to have a tensile strength of 200 to 300 N / mm. ² It is desirable to perform annealing so that the elongation becomes 30% or more. Further, in order to perform bending with a small bending radius on a composite heat transfer tube manufactured by fitting a small-diameter tube, the average crystal grain size in a section parallel to the tube axis of the large-diameter tube after annealing is preferably 30 μm or less (preferably 20 μm or less). ) Is advantageous because cracking due to bending is suppressed. In the case of other materials, it is preferable to perform annealing so that the elongation of the large-diameter pipe after annealing is 30% or more.
[0104]
Further, the annealing apparatus is not particularly limited, such as continuous annealing using a high-frequency induction heating furnace or a batch type furnace. However, the atmosphere may be adjusted so that a thick oxide film is not formed on the surface of the large-diameter tube 2 due to the annealing. is necessary. This is because the oxide film becomes a thermal resistance at a contact portion between the large-diameter tube 2 and each small-diameter tube 3.
[0105]
(3) Rolling fitting process
As shown in FIGS. 9, 10 (a) and 10 (b), three or four small-diameter tubes 3 are placed in three or four groove portions 4 and are rolled by one set of rolling rolls 16, 16. Then, each small-diameter tube 3 is embedded in each groove portion 4, and the annealed large-diameter tube 2 and each small-diameter tube 3 are fitted. Then, as shown in FIGS. 11A and 11B, the projections 4 a, 4 a formed at the upper end of each groove 4 of the large-diameter pipe 2 are rolled by the rolling rolls 16, 16 so that the small-diameter projections 4 a, 4 a are formed. The small-diameter pipes 3 are firmly fixed in the respective grooves 4 of the large-diameter pipe 2 by covering the outer surfaces of the pipes 3 (the respective small-diameter pipes 3 adhere to the respective grooves 4). The materials of the rolling rolls 16 and 16 may be the same as those used in a general rolling mill. Furthermore, after fitting by a predetermined length, by expanding the interval between the rolling rolls 16, fitting is not performed on a portion where each groove 4 is not formed.
[0106]
Further, it is preferable to use an appropriate lubricant for the rolling fitting and to remove the lubricating oil attached after the fitting is completed. Further, this rolling fitting may be performed a plurality of times. Then, before rolling by the rolling rolls 16, 16, an auxiliary roll or a die (not shown) for pushing each small-diameter pipe 3 placed in each groove 4 of the large-diameter pipe 2 into each groove 4 may be provided. .
[0107]
Further, in the cross section including the roll shafts of the rolling rolls 16, 16, a portion in contact with the large-diameter pipe 2 and each of the small-diameter pipes 3 is configured by a circle having an outer diameter d that is the same as or slightly smaller than the large-diameter pipe 2 ( d ≦ outer diameter of the large-diameter tube 2). When the outer diameter d is smaller than the outer diameter of the large-diameter pipe 2, each small-diameter pipe 3 is fitted to the large-diameter pipe 2, and at the same time, the outer diameter of the large-diameter pipe 2 is close to the outer diameter d. The diameter is reduced to the value. When the outer diameter d exceeds the outer diameter of the large-diameter pipe 2, the small-diameter pipes 3 do not adhere to the large-diameter pipe 2 (the surface 4A of each groove 4), and the large-diameter pipe 2 and each small-diameter pipe 3 There is a large gap between the two, and the fitting tends to be insufficient. In addition, as shown in FIGS. 13 and 16, in the composite heat transfer tubes 31, 41, 61 in which the winding portions 31 k, 41 k, 61 k are formed, the height H of the winding portions 31 k, 41 k, 61 k, In order to reduce the diameter OD, when the outer shape of the large-diameter tube 2 in a cross section orthogonal to the tube axis is made to be a flat circle, a portion in contact with the large-diameter tube 2 and each small-diameter tube 3 is a flat circle (an elliptical shape: Roll-fitting is performed by rolling rolls (not shown) configured for the large-diameter pipe 52 in FIG. 14C and the large-diameter pipe 72 in FIG. 16B.
[0108]
Further, according to the manufacturing method of the present invention, as shown in FIGS. 8 and 10, the large-diameter pipe 2 and each small-diameter pipe 3 are copper pipes or copper alloy pipes made of oxygen-free copper or phosphorous deoxidized copper. The diameter pipe 2 has a 0.2% proof stress of 200 to 370 N / mm in the pipe axis direction before forming each groove 4 on its outer surface. ² Each small-diameter pipe 3 has a 0.2% proof stress of 200 N / mm in the pipe axis direction. ² It is preferable that it is above.
[0109]
(Tempering of large diameter pipe before groove processing)
The large-diameter pipe 2 has a 0.2% proof stress of 200 to 370 N / mm in the pipe axis direction. ² It is preferable to use a refined material having the following condition. 0.2% proof stress 200N / mm ² If it is less than 10 mm, the large diameter pipe 2 cannot support the load when the groove 4 is machined by the pin 10, the periphery of the portion where the pin 10 is in contact is also deformed, and a wide area is depressed. It is difficult to form the grooves 4 correctly in the second groove 2. Therefore, it is difficult to fit the small diameter pipes 3 with a small gap.
[0110]
The large-diameter pipe 2 has a 0.2% proof stress of 370 N / mm. ² Exceeds, the strength of the large-diameter pipe 2 increases, making it difficult to form each groove 4 (the depth of the groove formed by one processing becomes shallow), lowering the efficiency of forming each groove, Further, the pin 10 is easily damaged.
[0111]
In addition, in addition to the above conditions, a 0.2% proof stress (σ _0.2 ) And tensile strength (σ _B ) And the ratio (σ _0.2 / Σ _B ) Of 0.80 or more and elongation of 5 to 40% is more preferably used.
[0112]
(Tempering of small diameter pipe to be fitted)
0.2% proof stress of 200N / mm in tube axis direction ² It is preferable to use the small-diameter tubes 3 having the above-mentioned tempering. Each small diameter pipe 3 has a 0.2% proof stress of 200 N / mm. ² When the smaller diameter pipes are used, the smaller diameter pipes 3 are likely to be deformed or flawed when the respective smaller diameter pipes 3 are fitted to the larger diameter pipes 2. For this reason, the gap between the large-diameter pipe 2 and each small-diameter pipe 3 increases, and the heat transfer performance tends to decrease. Further, due to the deformation of the pipe, the cross-sectional area in the pipe becomes small, and the pressure loss of the heat medium flowing in each small-diameter pipe 3 becomes large.
[0113]
In addition, in addition to the above conditions, a 0.2% proof stress (σ _0.2 ) And tensile strength (σ _B ) And the ratio (σ _0.2 / Σ _B ) Is more preferably 0.70 or more.
[0114]
Further, as shown in FIGS. 13 to 16, after the rolling fitting step, the manufacturing method of the present invention is configured such that the large-diameter pipes 2, 52, 72 fitted with the small-diameter pipes 3, 53, 73 are fixed. It is preferable to perform at least one of a winding step of winding at a radius, a pipe expanding step of expanding the pipe ends of the large diameter pipes 2, 52, 72 or / and the small diameter pipes 3, 53, 73, and an annealing step. . Further, final annealing may be performed after the above step.
[0115]
In the winding process, a cylindrical drum (not shown) is used to form the spiral winding portions 31k, 41k, and 51k, and a conical drum (not shown) is used to form the spiral winding portions 61k and 71k. (Not shown), the large-diameter pipes 2, 52, 72, into which the small-diameter pipes 3, 53, 73 have been fitted by the rolling fit, are wound around a drum. The diameter of the drum is set in consideration of the amount of springback of the large-diameter pipes 2, 52, 72. That is, the large-diameter pipes 2, 52, and 72 are spring-backed to have the minimum inner diameter ID and / or the maximum outer diameter OD (see FIGS. 14 and 16) of the winding portions 31k, 41k, 51k, 61k, and 71k. Set.
[0116]
As shown in FIGS. 4, 5 and 6, when three or four small-diameter tubes 3 are fitted in the circumferential direction of the large-diameter tube 2, the cross section of the large-diameter tube 2 orthogonal to the tube axis is reduced. It is preferable to wind the small-diameter pipes 3 so as to be arranged in the vertical direction. In this case, the winding lengths of the small diameter pipes 3 in the vertical direction are equal, which is convenient. As shown in FIGS. 2, 3, 4, and 6, when three or four small-diameter tubes 3 are fitted in the circumferential direction of the large-diameter tube 2, depending on the size of the winding diameter, Each small-diameter tube 3 arranged on the outer peripheral portion may come off from the large-diameter tube 2. In such a case, each small-diameter tube 3 is wound so as to be arranged on the center of the winding so as to increase the winding diameter. Alternatively, the large-diameter pipe fitted with the small-diameter pipe is annealed before winding.
[0117]
In the tube expanding step, the tube ends of the large-diameter tubes 2, 52, 72 and / or the small-diameter tubes 3, 53, 73 are expanded using a generally-used expanding device (not shown). When the composite heat transfer tube 1 is incorporated into the heat exchanger 20 (see FIG. 12) by this expansion, the large-diameter tubes 2, 52, 72 or / and the small-diameter tubes 3, 53, 73 are brazed and soldered to other tubes. For example, it becomes easy to join.
[0118]
In the annealing step, the winding portions 31k, 41k, 51k, 61k, and 71k are wound around the large-diameter pipes 2, 52, and 72 fitted with the small-diameter pipes 3, 53, and 73 or the large-diameter pipes 2, 52, and 72, respectively. The composite heat transfer tubes 1, 31, 41, 51, 61, 71 formed with are annealed under appropriate conditions. The large-diameter pipes 2, 52, and 72 after the rolling fitting step have semi-rigid grooves and are soft in other parts, and the small-diameter pipes 3, 53, and 73 are hard. When further winding the large diameter pipes 2, 52, 72, if the winding diameter (minimum inner diameter ID, maximum outer diameter OD in FIGS. 14 and 16) is small, if it is desired to perform the winding with high accuracy, When the ductility of the small-diameter pipes 3, 53, 73 is small, it is desirable that the large-diameter pipes 2, 52, 72 and the small-diameter pipes 3, 53, 73 be softened by annealing even if slightly. Also, when the composite heat transfer tubes 1, 31, 41, 51, 61, 71 are attached to the heat exchanger 20 (see FIG. 12), bending is often performed, and in order to satisfy severe bending workability, It is better that the large-diameter pipes 2, 52, 72 and the small-diameter pipes 3, 53, 73 are softened at least by annealing.
[0119]
By this annealing, the stresses of the large-diameter pipes 2, 52, 72 and the small-diameter pipes 3, 53, 73 are removed, and the winding portions 31k, 41k, 51k, 61k, 71k are compacted in the height (H) direction. . When incorporated in the heat exchanger 20 (see FIG. 6), the large-diameter pipes 2, 52, 72 and the small-diameter pipes 3, 53, 73 can be easily bent and deformed and joined to other pipes. And stress corrosion cracking is less likely to occur.
[0120]
If the material of the large-diameter pipes 2, 52, 72 and / or the small-diameter pipes 3, 53, 73 is oxygen-free copper or phosphorous deoxidized copper, the composite heat transfer tubes 1, 31, produced by the above-described manufacturing method. 41, 51, 61 and 71 are held at a temperature of 200 to 500 ° C. for about 10 seconds to 2 hours. Thereby, the composite heat transfer tubes 1, 31, 41, 51, 61, 71 become softer, and the desired workability is provided.
[0121]
Further, another manufacturing method of the present invention will be described. Another manufacturing method includes a groove portion forming step, an annealing step, a resin applying step, a rolling fitting step, and a resin curing step.
[0122]
(Groove forming step) This is performed in the same manner as in the above-described manufacturing method.
(Annealing step) This is performed in the same manner as in the above-mentioned manufacturing method.
(Resin coating process)
An appropriate resin 5 is selected from the above-mentioned resins 5 such as polyethylene glycol and organic-inorganic hybrid ceramics, and adjusted to an appropriate viscosity. This resin 5 is fitted to at least a part of the surface of each of the three or four groove portions 4 formed on the large-diameter tube, or the large-diameter tube 2 on the outer surface of each of the three or four small-diameter tubes 3. At least a part of the portion to be coated is applied by a suitable method such as spraying, ink jet, or brush. (See FIG. 11 (c))
[0123]
(Rolling fitting process)
Before the resin 5 is cured, each small-diameter pipe 3 is roll-fitted to the large-diameter pipe 2 through the resin 5 before the resin 5 is cured. In addition, the resin 5 protruding from each groove portion 4 by rolling fitting is removed by a blower or the like. Further, if the resin 5 itself does not adversely affect the corrosion resistance of the composite heat transfer tube 1 or the like, it is not necessary to remove the resin.
[0124]
(Resin curing process)
The composite heat transfer tube 1 produced in the rolling fitting step is subjected to a degreasing treatment, and is heated to a curing temperature (preferably 200 ° C. or less) of the resin 5 by a generally used heater (not shown). The resin 5 between the large-diameter tube 2 and each small-diameter tube 3 is cured by heating for a predetermined time. Due to the curing of the resin 5, the large-diameter pipe 2 and each small-diameter pipe 3 are sufficiently fitted, and a fine gap between the large-diameter pipe 2 and each small-diameter pipe 3 can be filled. The thermal performance is improved (see FIG. 11C).
[0125]
Further, similarly to the manufacturing method, after the rolling fitting step, a winding step of winding the large diameter pipes 2, 52, 72 fitted with the small diameter pipes 3, 53, 73 at a predetermined radius, It is preferable to perform at least one of a pipe expansion step of expanding the pipe ends of the large diameter pipes 2, 52, 72 or / and the small diameter pipes 3, 53, 73 and an annealing step. Further, the resin curing step may be performed after the winding step. Further, final annealing may be performed.
[0126]
Next, an example of use of the composite heat transfer tube of the present invention will be described with reference to FIG. FIG. 12 shows a heat exchanger 20 for a refrigerator using the gas compression cooling principle. Refrigerant (for example, CFC substitute gas) in the heat exchanger 20 is compressed by the compressor 21 to become a high-pressure gas, which is lowered in temperature by the radiator 22 to become a liquid. Then, in the cooler 23, the liquid is vaporized by being rapidly decompressed (expanded). Since a large amount of ambient heat is removed by this vaporization, the inside of the refrigerator provided with the heat exchanger 20 is cooled by this vaporization heat. Then, the refrigerant becomes low-temperature low-pressure gas and returns to the compressor 21.
[0127]
In the composite heat transfer tube 1 of the present invention incorporated in the heat exchanger 20, three or four small-diameter tubes 3 are interposed between the radiator 22 and the cooler 23 so that the compressor 21 The large-diameter pipe 2 is interposed between them. Then, in each small-diameter pipe 3, the pressure of the liquid refrigerant is adjusted by reducing the pipe diameter. At the same time, the temperature of the liquid refrigerant that could not be completely removed by the radiator 22 alone is reduced and exchanged by the low-temperature and low-pressure refrigerant gas flowing in the large-diameter tube 2. Thereby, the liquid refrigerant is adjusted to a temperature and pressure suitable for vaporization in the cooler 23. On the other hand, in the large-diameter pipe 2, the low-temperature and low-pressure refrigerant gas flowing in the large-diameter pipe 2 undergoes heat exchange with the medium-temperature and low-pressure liquid refrigerant flowing in each small-diameter pipe 3 so as to have a high temperature. As described above, by using the composite heat transfer tube 1, the refrigerant is efficiently liquefied and vaporized in the heat exchanger 20.
[0128]
Also, water is flowed through the large-diameter pipe 2 of the composite heat transfer tube 1 of the present invention, and high-temperature and high-pressure CO ₂ It is also possible to use it as a heat pump water heater for heating water in the large-diameter pipe 2 or a heat exchanger for floor heating by flowing water.
[0129]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
(First Embodiment) Embodiments 1 to 6
(1) Preparation of composite heat transfer tube
In the following procedure, t / T is changed in six stages shown in Table 3, and the large-diameter pipe is separated by 120 ° in the circumferential direction of the cross section orthogonal to the pipe axis (positions at equal intervals in the cross section orthogonal to the pipe axis). Each of four composite heat transfer tubes (Examples 1 to 6) in which three small-diameter tubes were fitted was manufactured.
[0130]
(1-1) Groove formation of large diameter pipe
Table 1 was used for the large diameter pipe. As the material of the large-diameter tube, phosphorous deoxidized copper of alloy number C1220 specified in JIS H3300 was used. Further, the pin 10 shown in Table 2 and FIG. 8B was used for forming the groove. By fixing the pin 10 and moving the large-diameter tube 2, the grooves 4, 4, 4 were formed at three locations separated by 120 ° in the cross section orthogonal to the tube axis of the large-diameter tube 2. The grooves 4 were formed by dropping the lubricating oil (not shown) while excluding 100 mm at both ends with respect to the entire length of the large-diameter pipe 2.
[0131]
Further, in this embodiment, t / T described later was changed by changing the pressing load of the pin. Further, by moving the large-diameter pipe 2 once or a plurality of times, three grooves 4, 4, and 4 were formed in the large-diameter pipe 2 a plurality of times, and each of the grooves 4 having a predetermined depth was formed. Further, each time the number of movements of the large diameter pipe 2 increases, the length of the groove 4 is shortened so that both ends of the groove 4 are stepped. Also, when forming each groove 4, fine chips are generated in each groove 4, so that the pin 10 is worn and the contact state with a small-diameter pipe (not shown) is improved (see FIG. 9). The chips were removed using a blower (not shown).
[0132]
(1-2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. The large-diameter pipe after annealing softens and has a tensile strength of 240 to 249 N / mm. ² , 0.2% proof stress is 73-78N / mm ² The elongation was 48 to 49.5% and the average crystal grain size (section parallel to the tube axis) was 23 to 27 μm.
[0133]
(1-3) Fitting of small diameter pipe
Table 1 was used for the small diameter pipe. As the material of the small-diameter tube, phosphorous deoxidized copper of alloy number C1220 specified in JIS H3300 was used. As shown in FIG. 10 (b), three small-diameter pipes 3, 3, 3 are lightly fitted into three groove portions 4, 4, 4 formed in the large-diameter pipe 2, and are passed through rolling rolls 16, 16. . As a result, a composite heat transfer tube 1 in which three small-diameter tubes 3, 3, and 3 were fitted at a position 120 ° apart from the tube axis orthogonal cross section of the large-diameter tube 2 was produced.
[0134]
(2) Evaluation items
For one of the four composite heat transfer tubes prepared above, a groove of 5000 mm in length was cut into 500 mm pieces to make 10 samples, and the t / T, heat transfer performance, and bending workability were investigated. did. The pressure resistance was investigated using the remaining three pieces.
(2-1) t / T
As shown in FIG. 2, t is the thickness t1, t2, t3 of the groove bottom portions 4b, 4b, 4b of the three grooves 4, 4, 4 fitted with the small diameter pipes 3, 3, 3. Average value. In addition, T is an average value of the thicknesses T1, T2, and T3 of three places of the large-diameter pipe 2 not fitted to the small-diameter pipes 3, 3, 3 shown in FIG. Of the 5000 mm long groove, samples of about 10 mm thickness were taken from three places of 500 mm and 2500 mm from both ends, the tube axis orthogonal cross section was observed with an optical microscope, and the thickness t1 to t3, T1 at each position. T3 was measured, and t / T was calculated from their average value.
[0135]
(2-2) Heat transfer performance
Evaluation is made based on the state of close contact between the large-diameter pipe and the small-diameter pipe in the groove. With respect to the ten samples cut into the above-mentioned 500 mm each, the adhesion state between the large-diameter pipe and the small-diameter pipe in the groove was observed with an optical microscope at nine pipe axis orthogonal cross sections except both ends. Table 3 shows the results. In addition, when the gap between the large-diameter pipe and the small-diameter pipe is small and small, the heat transfer performance is excellent (「), and when the gap is not large, the heat transfer performance is good (△). In addition, those having a large number of generated gaps were evaluated as “X” having poor heat transfer performance.
[0136]
(2-3) Bendability
The bending workability was evaluated by a bending test. The bending test was performed using the sample cut to the length of 500 mm. The sample was bent in a U-shape along a bending jig having a radius of 30 mm, and it was evaluated whether the small-diameter pipe was removed from the large-diameter pipe. In addition, as shown in FIG. 2, in the cross section orthogonal to the tube axis of the composite heat transfer tube 1, the tube was bent such that the one-dot chain line (YY line) becomes a bending neutral axis. Evaluation was performed with the sample number n = 5, and the number of small-diameter tubes detached was recorded. Table 3 shows the results.
[0137]
(2-4) Compressive strength
Water was filled into the large-diameter tube of the uncut composite heat transfer tube and gradually pressurized with a hand pump, and the pressure at which the small-diameter tube began to separate from the large-diameter tube was read with a Bourdon tube gauge. Evaluation was performed using the average value of n = 3, and the results are shown in Table 3.
[0138]
[Table 1]

[0139]
[Table 2]

[0140]
[Table 3]

[0141]
(3) Evaluation results
In the first embodiment, since the t / T is smaller than the other embodiments 2 to 6 and the groove formed in the large-diameter pipe is deeper, the protrusions 4a, 4a ( FIG. 11) was long, and the adhesion state of this portion was good. Then, a gap was formed at a position corresponding to the groove bottom portions 4b, 4b, 4b (see FIG. 2), but the gap was not large and the heat transfer performance was good. Further, the thickness t1, t2, t3 (see FIG. 2) of the large-diameter pipe in the groove bottom portions 4b, 4b, 4b (see FIG. 2) is reduced, so that it is 10 to 30 as compared with the other embodiments 2 to 6. % Pressure resistance is low.
[0142]
In Examples 2 to 5, heat transfer performance, bending workability, and pressure resistance were all excellent.
In the sixth embodiment, the t / T is larger than the other embodiments 1 to 5, and the groove formed in the large-diameter tube is shallower. Therefore, the large-diameter tube 2 (surface 4A) and the small-diameter tube 3 ( The contact length of the arc 3A) was shortened (see FIG. 2), and the close contact condition of the projections 4a, 4a (see FIG. 11) of the large-diameter pipe was good. Then, a gap was formed in other portions, but the gap was not large, and the heat transfer performance was good. Further, since the groove portion was shallow, the small-diameter fitting force became small, and the small-diameter tube was separated from one composite heat transfer tube in the bending test (the small-diameter tube outside the bend).
[0143]
From these results, it is understood that t / T is preferably in the range of 0.3 to 0.7 in order to satisfy all of the heat transfer performance, bending workability, and pressure resistance.
[0144]
(Second Embodiment) Embodiments 7 and 8
(1) Preparation of composite heat transfer tube
According to the following procedure, t / T was the same as in Examples 1 and 3, and one composite heat transfer tube in which a large-diameter pipe and a small-diameter pipe were fitted via a resin was manufactured one by one. 7 and Example 8.
(1-1) Groove formation of large diameter pipe
The procedure for forming the large-diameter pipe, pins and grooves used is the same as in the first embodiment.
[0145]
(1-2) Annealing of large-diameter pipe with groove formed
This is the same as the first embodiment.
[0146]
(1-3) Application of resin
Polyethylene glycol was used as the resin. The resin was diluted with water to a concentration that would be easy to apply. Further, in order to check the presence of the resin in the groove, the resin was colored with blue ink and applied to the groove formed in the large-diameter tube.
[0147]
(1-4) Fitting of small diameter pipe
The small diameter pipe used is the same as in the first embodiment. Then, a small-diameter pipe was fitted in the same manner as in the first embodiment, and excess resin extruded from the groove was wiped off.
[0148]
(1-5) Curing of resin
The large-diameter tube fitted with the small-diameter tube was placed in a furnace at 200 ° C. maintained in a non-oxidizing atmosphere, heated for a predetermined time (0.5 hour), and the resin was cured to obtain a composite heat transfer tube.
[0149]
(2) Evaluation items
The t / T, the heat transfer performance, and the bending workability were evaluated in the same manner as in the first example, and the results are shown in Table 4.
[0150]
[Table 4]

[0151]
(3) Evaluation results
In the composite heat transfer tube of Example 1, it was observed that a gap was formed at a position corresponding to the groove bottom. In the composite heat transfer tube of the seventh embodiment having the same value of t / T as that of the first embodiment, the portion where the gap exists is filled with the resin, and the large-diameter tube and the small-diameter tube adhere directly or by resin. ing. For this reason, the heat transfer performance was excellent. In addition, the bending workability was good even when the resin was present.
[0152]
The composite heat transfer tube of Example 3 had small and small gaps. In the composite heat transfer tube of Example 8 having the same value of t / T as that of Example 3, it was confirmed that the resin was also present in the minute gap portion, and the heat transfer performance was excellent. . Further, similarly to Example 7, even in the presence of the resin, the bending workability was good.
[0153]
From these results, the presence of the resin between the large-diameter pipe and the small-diameter pipe eliminates the air layer that becomes the thermal resistance and reduces the thermal resistance, resulting in excellent heat transfer performance. It was found that there was no adverse effect on bending workability.
[0154]
(Third Embodiment) Embodiments 9 to 11
(1) Preparation of composite heat transfer tube
In the following procedure, three composite heat transfer tubes having the same t / T as in Example 8 but having a large-diameter tube and a small-diameter tube fitted via a different resin (ceramic) from Example 8 were manufactured and implemented. Examples 9 to 11 were used.
(1-1) Groove formation of large diameter pipe
The procedure for forming the large-diameter pipe, pins and grooves used is the same as in the first embodiment.
[0155]
(1-2) Annealing of large-diameter pipe with groove formed
This is the same as the first embodiment.
[0156]
(1-3) Application of resin (ceramics)
As a resin (ceramics) to be applied, a glassware HPC7506 solution manufactured by JSR (a density of 1.5 × 10 ³ kg / m ³ )It was used. When this ceramic is cured by heating, it becomes an organic-inorganic hybrid ceramic. Then, the HPC7506 solution was diluted to an appropriate concentration with a solvent, and the diluted solution was applied to the groove of the large-diameter tube. ₂ O ₃ 15 vol% of the particles were added, diluted to an appropriate concentration with a solvent, and applied to the groove of the large diameter tube in Example 10. The HPC7506 solution was added with 10 vol% of 350 mesh under electrolytic copper powder and adjusted to an appropriate concentration with a solvent. Example 11 was obtained by diluting the solution and applying the solution to the groove of the large-diameter tube.
[0157]
(1-4) Fitting of small diameter pipe
The small diameter pipe used is the same as in the first embodiment. Then, a small-diameter tube was fitted in the same manner as in the first embodiment, and excess resin (ceramics) extruded from the fitting portion was wiped off.
(1-5) Curing of resin (ceramics)
The large-diameter pipe fitted with the small-diameter pipe was charged into a 100 ° C. furnace maintained in a non-oxidizing atmosphere, and the resin (ceramics) was cured to obtain a composite heat transfer pipe.
[0158]
(2) Evaluation items
The t / T, the heat transfer performance, and the bending workability were evaluated in the same manner as in the first example, and the results are shown in Table 5.
[0159]
[Table 5]

[0160]
(3) Evaluation results
As shown in Table 5, in any of the composite heat transfer tubes of Examples 9 to 11, a fine gap between the small-diameter tube and the large-diameter tube has a ceramic layer or metal oxide particles (metal particles). ) Is present, and there is no air layer serving as thermal resistance. As a result, the heat resistance is reduced, and the heat transfer performance is excellent. Also, it was found that the bending workability was not adversely affected.
[0161]
(Fourth Embodiment) Embodiments 12 to 15
(1) Preparation of composite heat transfer tube
In the following procedure, as shown in Table 7, t / T is changed in four steps, and three small-diameter pipes are fitted at positions 60 ° apart in the pipe circumferential direction in a cross section orthogonal to the pipe axis of the large-diameter pipe. Four composite heat transfer tubes (Examples 12 to 15) were manufactured.
[0162]
(1-1) Groove formation of large diameter pipe
Table 8 was used for the large diameter tube. As the material of the large-diameter tube, phosphorous deoxidized copper of alloy number C1201 specified in JIS H3300 was used. The pins shown in Table 6 were used for forming the grooves. 8B, the position of the lower pin 10 is kept as it is, and the upper pin 10, 10 is moved from the lower pin 10 by 60 ° in the circumferential direction of the large-diameter tube 2 in FIG. 8B. Those that were arranged at distant positions were used. The other points were the same as in the first embodiment.
[0163]
(1-2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. After annealing, the large-diameter pipe softens and has a tensile strength of 243 to 250 N / mm. ² , 0.2% proof stress is 78-81N / mm ² The elongation was 51 to 53%, and the average crystal grain size (section parallel to the tube axis) was 23 to 25 μm.
[0164]
(1-3) Fitting of small diameter pipe
Table 8 was used for the small diameter tube. As the material of the small-diameter tube, phosphorous deoxidized copper of alloy number C1220 specified in JIS H3300 was used. Three small-diameter pipes were each lightly fitted into three grooves formed in the large-diameter pipe, and were passed through a rolling roll so that the three small-diameter pipes hit the upper roll. Thus, a composite heat transfer tube in which three small-diameter tubes were fitted at positions separated by 60 ° in the circumferential direction of the large-diameter tube in a section orthogonal to the tube axis was produced.
[0165]
(2) Evaluation items
For one of the four composite heat transfer tubes prepared above, a groove having a length of 8000 mm was cut into 800 mm pieces to prepare 10 samples, and t / T, heat transfer performance, and bending workability were investigated. . The pressure resistance was investigated using the remaining three pieces.
(2-1) t / T
As shown in FIG. 3, t is the thickness t1, t2 of the groove bottom portions 4b, 4b, 4b of the three grooves 4, 4, 4 fitted to the three small diameter tubes 3, 3, 3. , T3. In addition, T is a thickness T1 at a predetermined position of the large-diameter pipe 2 that is not fitted with each small-diameter pipe 3 shown in FIG. Of the groove having a length of 8000 mm, samples having a thickness of about 10 mm were collected from three places of 800 mm and 4000 mm from both ends, and the tube axis orthogonal cross section was observed with an optical microscope, and the thicknesses t1, t2, t3, T1 was measured, and t / T was calculated from the average value thereof.
[0166]
(2-2) Heat transfer performance
Evaluation is made based on the state of close contact between the large-diameter pipe and the small-diameter pipe in the groove. In the ten samples cut at 800 mm intervals, the adhesion between the large-diameter pipe and the small-diameter pipe in the groove was observed with an optical microscope at nine pipe axis cross sections except for both ends. Table 7 shows the results. In addition, when the gap between the large-diameter pipe and the small-diameter pipe is small and small, the heat transfer performance is excellent (「), and when the gap is not large, the heat transfer performance is good (△). In addition, those having a large number of generated gaps were evaluated as “X” having poor heat transfer performance.
[0167]
(2-3) Bendability
The bending workability was evaluated by a bending test. The bending test was performed using the sample cut to the length of 800 mm. The sample was bent in a U-shape along a bending jig having a radius of 60 mm, and it was evaluated whether or not the small-diameter pipe was removed from the large-diameter pipe. As shown in FIG. 3, in the cross section orthogonal to the tube axis of the composite heat transfer tube 1, an alternate long and short dash line (Y-Y line) becomes a neutral axis of bending (three small-diameter pipes 3, 3, 3 b ). Investigation was performed at n = 5, and the number of small-diameter tubes detached was recorded. Table 7 shows the results.
[0168]
(2-4) Compressive strength
Same as the method of the first embodiment. Table 7 shows the results.
[0169]
[Table 6]

[0170]
[Table 7]

[0171]
[Table 8]

[0172]
(3) Evaluation results
As shown in Table 7, in Example 12, the t / T was smaller than the other samples, and the groove formed in the large-diameter pipe became deeper. Was good. Then, a gap was formed at a position corresponding to the groove bottom, but the gap was not large and the heat transfer performance was good. In addition, the thickness of the large-diameter pipe at the groove bottom is reduced, so that the pressure resistance is lower than that of other samples.
[0173]
Example 13 and Example 14 were excellent in heat transfer performance, bending workability, and pressure resistance.
[0174]
In Example 15, the t / T was larger than the other samples, and the groove formed in the large-diameter tube became shallower. Although the state of adhesion was good, gaps were formed in other parts. The gap was not large, and the heat transfer performance was good. In Example 15, although the fitting force was small, even when the small-diameter pipe was bent so as to come to the inner side surface of the bend in the bending cross section, none of the small-diameter pipes separated from the composite heat transfer pipe.
[0175]
(Fifth Embodiment) Embodiment 16
(1) Preparation of composite heat transfer tube
In the following procedure, three small-diameter pipes were fitted at positions 120 ° apart from each other in the pipe circumferential direction of the large-diameter pipe made of a copper alloy in the pipe-circumferential cross-section (positions at equal intervals in the pipe-axis cross-section). Four composite heat transfer tubes (Example 16) were produced.
[0176]
(1-1) Groove formation of large diameter pipe
Same as the first embodiment. However, the large-diameter pipe used was that shown in Table 9, and the material used was a copper alloy of 0.65% by mass Sn, 0.027% by mass P, 0.35% by mass Zn, and the balance Cu.
[0177]
(1-2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. The large-diameter pipe after annealing softens and has a tensile strength of 322 N / mm ² , 0.2% proof stress is 128N / mm ² The elongation was 43% and the average crystal grain size (section parallel to the tube axis) was 15 μm.
[0178]
(1-3) Fitting of small diameter pipe
The small-diameter pipes shown in Table 1 were used, and the fitting method was the same as in the first embodiment.
[0179]
(2) Evaluation items
Same as the first embodiment. Table 10 shows the results.
(3) Evaluation results
As shown in Table 10, the composite heat transfer tube of Example 16 had excellent heat transfer performance and bending workability. In addition, since the alloy pipe was used for the large-diameter pipe, the pressure resistance was significantly improved as compared with the composite heat transfer pipe of Example 4 having substantially the same t / T.
[0180]
[Table 9]

[0181]
[Table 10]

[0182]
(Sixth Embodiment) Embodiment 17
(1) Preparation of composite heat transfer tube
In the following procedure, aluminum alloy tubes or aluminum tubes having the materials and mechanical properties shown in Table 11 were used as the large-diameter tube and the small-diameter tube. One fitted composite heat transfer tube (Example 17) was produced.
[0183]
(1-1) Groove formation of large diameter pipe
Same as the first embodiment. However, the thing of Table 11 was used for the large diameter pipe, and the material used the Al-Mg type alloy of alloy number A5052 prescribed | regulated to JISH4000.
[0184]
(1-2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. After annealing, the large-diameter pipe softens and has a tensile strength of 187 N / mm. ² , 0.2% proof stress is 87N / mm ² , The growth was 31%.
[0185]
(1-3) Fitting of small diameter pipe
Same as the first embodiment. However, the small-diameter pipe used was that shown in Table 11, and the material used was pure aluminum of alloy number A1100 specified in JIS H4000.
[0186]
(2) Evaluation items
Same as the first embodiment. However, the withstand voltage test was not evaluated. Table 12 shows the results.
[0187]
[Table 11]

[0188]
[Table 12]

[0189]
(3) Evaluation results
As shown in Table 12, the composite heat transfer tube of Example 17 had excellent heat transfer performance and bending workability.
[0190]
(Seventh embodiment) Embodiment 18
(1) Preparation of composite heat transfer tube
According to the following procedure, four composite heat transfer tubes (Example 18) in which three small-diameter tubes were fitted to the large-diameter tube using the inner grooved tube as the large-diameter tube were produced.
[0191]
(1-1) Groove formation of large diameter pipe
Same as the first embodiment. However, the large-diameter pipe used was that shown in Table 13, and the material used was phosphorous deoxidized copper of alloy number C1220 specified in JIS H3300. The inner surface used had a lead angle of 25 °, 55 grooves, a groove depth of 0.23 mm, and a crest angle of 30 °.
[0192]
(2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. After annealing, the large-diameter pipe softens and has a tensile strength of 227 N / mm. ² , 0.2% proof stress is 70N / mm ² The elongation was 49% and the average crystal grain size (section parallel to the tube axis) was 20 μm.
[0193]
(1-3) Fitting of small diameter pipe
The small-diameter pipes shown in Table 1 were used, and the fitting method was the same as in the first embodiment.
(2) Evaluation items
Same as the first embodiment. Table 14 shows the results.
[0194]
[Table 13]

[0195]
[Table 14]

[0196]
(3) Evaluation results
As shown in Table 14, Example 18 was excellent in heat transfer performance, bending workability, and pressure resistance.
[0197]
(Eighth embodiment) Examples 19 to 27, Comparative Example 1, Comparative Example 2
(1) Preparation of composite heat transfer tube
A composite heat transfer tube (Examples 19 to 27) in which three small diameter tubes having a specific 0.2% proof stress are fitted to a large diameter tube having a specific 0.2% proof stress by the following procedure. Produced. Further, composite heat transfer tubes (Comparative Example 1, Comparative Example 2) using large-diameter tubes that were not subjected to annealing were also manufactured.
[0198]
(1-1) Groove formation of large diameter pipe
Same as the first embodiment. However, the large-diameter pipe used in Table 15 was used, and as the material thereof, phosphorus deoxidized copper of alloy number C1201 specified in JIS H3300 was used, and the total length was 5,200 mm. Also, the pins used in Table 16 were used, and the movement of the large-diameter pipe was designated as No. D1-No. D4 was performed 4 times (5000 mm × 4), D5 was performed 6 times (5000 mm × 6), and a groove was formed in a portion excluding the tube end of 100 mm. Then, in Table 15, No. The grooves were formed in four D3 large-diameter tubes and two in other large-diameter tubes. Table 17 shows the results of the groove formation.
[0199]
(1-2) Annealing of large-diameter pipe with groove formed
Two large-diameter pipes (No. D1 to No. D5 in Table 15) each having a groove were degreased and annealed in a non-oxidizing atmosphere using a roller hearth furnace. The large-diameter pipe after annealing softens and has a tensile strength of 208 to 250 N / mm. ² , 0.2% proof stress 56-77N / mm ² The elongation was 49 to 53% and the average crystal grain size (section parallel to the tube axis) was 20 to 30 μm. Then, in Table 15, No. The other two pieces of D3 were not annealed.
[0200]
(1-3) Fitting of small diameter pipe
Two types (Nos. S1 and S2) shown in Table 18 were used for the small diameter pipe, and the material thereof was phosphorus deoxidized copper of alloy number C1201 specified in JIS H3300. Then, the annealed No. No. D1 to D5 large-diameter pipes and No. Three small-diameter pipes of two types (Nos. S1 and S2) are each lightly fitted into the three grooves formed in the large-diameter pipe D3, and passed through a rolling roll as in the first embodiment. As a result, a composite heat transfer tube was manufactured in which three small diameter tubes were fitted at equidistant positions in the cross section orthogonal to the tube axis of the large diameter tube.
[0201]
(3) Evaluation items
Same as the first embodiment. However, excluding bending workability and pressure strength. Table 19 shows the results.
[0202]
[Table 15]

[0203]
[Table 16]

[0204]
[Table 17]

[0205]
[Table 18]

[0206]
[Table 19]

[0207]
(4) Evaluation results
As shown in Table 19, in Example 19, since the 0.2% proof stress of the large-diameter pipe was small, the portion other than the portion where the pin hit when the groove was formed was easily deformed, and the width was wide (a shape close to a V-shape). Was formed. However, when the small-diameter tube was fitted, the gap generated in the portion other than the projection of the large-diameter tube was not large, and the heat transfer performance was good. Also, in Example 20 using a soft small-diameter tube (S2), the small-diameter tube was deformed by rolling, but the generated gap was not large and the heat transfer performance was good.
[0208]
In Example 21, Example 23, and Example 25, since a hard small-diameter pipe (S1) was fitted, there was little generation of a gap, and the heat transfer performance was excellent. In Example 22 and Example 24, since a small-diameter tube (S2), which was soft, was fitted, the small-diameter tube was deformed by rolling, but the generated gap was not large and the heat transfer performance was good. Met.
[0209]
In Examples 26 and 27, since the large-diameter pipe was hard, it took time to form the groove. However, as in Examples 21 to 25, the generated gap was not large, and the heat transfer performance was good. there were.
[0210]
In Comparative Example 1 and Comparative Example 2, since the large-diameter pipe was not annealed, the small-diameter pipe was fitted to the large-diameter pipe in a hard state, and the small-diameter pipe was hard to enter the groove of the large-diameter pipe. The tube projection was not sufficiently covered with the small diameter tube. Therefore, many large gaps were formed at the bottom of the groove, and the heat transfer performance was poor.
[0211]
From the above description, as a large diameter pipe before forming a groove on the outer surface of the pipe, 0.2% proof stress σ in the pipe axis direction _0.2 Is 200 to 370 N / mm ² And a 0.2% proof stress σ as a small-diameter tube. _0.2 Is 200 N / mm ² It can be seen that it is preferable to use the above.
[0212]
(Ninth Embodiment) Embodiments 28 to 33
(1) Preparation of composite heat transfer tube
In the following procedure, t / T is changed in six stages shown in Table 21, and the large-diameter pipes are separated by 90 ° in the circumferential direction of the pipe axis orthogonal cross section (positions at equal intervals in the pipe axis orthogonal cross section). Each of four composite heat transfer tubes (Examples 28 to 33) in which four small-diameter tubes were fitted was manufactured.
[0213]
(1-1) Groove formation of large diameter pipe
Table 20 was used for the large diameter pipe. As the material of the large-diameter tube, phosphorous deoxidized copper of alloy number C1220 specified in JIS H3300 was used. Further, the pin 10 shown in Table 2 and FIG. 8A was used for forming the groove. By fixing the pin 10 and moving the large-diameter tube 2, grooves 4, 4, 4, 4 were formed at four locations separated by 90 ° in the cross section orthogonal to the tube axis of the large-diameter tube 2. The grooves 4 were formed by dropping the lubricating oil (not shown) while excluding 100 mm at both ends with respect to the entire length of the large-diameter pipe 2. Others are the same as the first embodiment.
[0214]
(1-2) Annealing of large-diameter pipe with groove formed
Same as the first embodiment. Tensile strength after annealing is 220-236N / mm ² , 0.2% proof stress is 71-74N / mm ² The elongation was 50 to 51.5% and the average crystal grain size (section parallel to the tube axis) was 22 to 25 μm.
[0215]
(1-3) Fitting of small diameter pipe
Table 20 was used for the small diameter pipe. As the material of the small-diameter tube, phosphorous deoxidized copper of alloy number C1220 specified in JIS H3300 was used. As shown in FIG. 10 (a), four small-diameter tubes 3, 3, 3, 3 are lightly fitted into four groove portions 4, 4, 4, 4 formed in the large-diameter tube 2, respectively. , 16. Thus, the composite heat transfer tube 1 in which the four small-diameter tubes 3, 3, 3, and 3 were fitted at a position 90 ° apart from the tube axis orthogonal cross section of the large-diameter tube 2 was produced.
[0216]
(2) Evaluation items
For one of the four composite heat transfer tubes prepared above, a groove of 5000 mm in length was cut into 500 mm pieces to make 10 samples, and the t / T, heat transfer performance, and bending workability were investigated. did. The pressure resistance was investigated using the remaining three pieces.
(2-1) t / T
As shown in FIG. 5, t is the thickness of the groove bottom portions 4b, 4b, 4b, 4b of the four grooves 4, 4, 4, 4 fitted with the small diameter pipes 3, 3, 3, 3. The average value of t1, t2, t3, and t4 is used. In addition, T is an average value of the thicknesses T1, T2, T3, and T4 of four locations of the large-diameter pipe 2 not fitted to the small-diameter pipes 3, 3, 3, and 3 shown in FIG. Of the groove of 5000 mm in length, samples with a thickness of about 10 mm were taken from three places of 500 mm and 2500 mm from both ends, and the tube axis orthogonal cross section was observed with an optical microscope, and the wall thicknesses t1 to t4, T1 at each position. T4 was measured, and t / T was calculated from the average value. The results are shown in Table 21.
[0219]
(2-2) Heat transfer performance
Same as the first embodiment. The results are shown in Table 21.
[0218]
(2-3) Bendability
Same as the first embodiment. The results are shown in Table 21.
[0219]
(2-4) Compressive strength
Same as the first embodiment. The results are shown in Table 21.
[0220]
[Table 20]

[0221]
[Table 21]

[0222]
(3) Evaluation results
In Example 28, since t / T was smaller than other Examples 29 to 33 and the groove formed in the large-diameter pipe became deeper, the projections 4a, 4a ( FIG. 11) was long, and the adhesion state of this portion was good. Then, a gap was formed at a position corresponding to the groove bottom portions 4b, 4b, 4b, 4b (see FIG. 5), but the gap was not large and the heat transfer performance was good. Further, the thickness t1, t2, t3, t4 (see FIG. 5) of the large-diameter pipe in the groove bottom portions 4b, 4b, 4b, 4b (see FIG. 5) is reduced, so that compared to the other embodiments 29 to 33. Pressure resistance is low by about 10 to 30%.
[0223]
Examples 29 to 32 were excellent in heat transfer performance, bending workability, and pressure resistance.
In Example 33, since t / T is larger than other Examples 28 to 32 and the groove formed in the large diameter pipe is shallower, the large diameter pipe 2 (surface 4A) and each small diameter pipe 3 (each small diameter pipe 3) in each groove 4 are provided. The contact length of the arc 3A) was shortened (see FIG. 5), and the close contact condition of the projections 4a, 4a (see FIG. 11) of the large-diameter pipe was good. Then, a gap was formed in other portions, but the gap was not large, and the heat transfer performance was good. In addition, the small-diameter fitting force was reduced due to the shallow groove portion, and the small-diameter tube was separated from the two composite heat transfer tubes in the bending test (the small-diameter tube outside the bend).
[0224]
From these results, it is understood that t / T is preferably in the range of 0.3 to 0.7 in order to satisfy all of the heat transfer performance, bending workability, and pressure resistance.
[0225]
(Tenth embodiment) Embodiments 34 and 35
(1) Preparation of composite heat transfer tube
In the same procedure as in the second embodiment, t / T is the same as in Examples 28 and 30 of Table 21, and a composite heat transfer tube in which a large-diameter tube and a small-diameter tube are fitted via a resin is 1 for each. These were manufactured one by one, and were referred to as Example 34 and Example 35, respectively.
(1-1) Groove formation of large diameter pipe
The procedure for forming the large-diameter pipe, pins and grooves used is the same as in the ninth embodiment.
[0226]
(1-2) Annealing of large-diameter pipe with groove formed
This is the same as the ninth embodiment.
[0227]
(1-3) Application of resin
Same as the second embodiment.
[0228]
(1-4) Fitting of small diameter pipe
The used small diameter pipe is the same as that of the ninth embodiment. Then, similarly to the ninth embodiment, a small-diameter pipe was fitted, and excess resin extruded from the groove was wiped off.
[0229]
(1-5) Curing of resin
The large-diameter tube fitted with the small-diameter tube was placed in a furnace at 200 ° C. maintained in a non-oxidizing atmosphere, heated for a predetermined time (0.5 hour), and the resin was cured to obtain a composite heat transfer tube.
[0230]
(2) Evaluation items
The t / T, the heat transfer performance, and the bending workability were evaluated in the same manner as in the ninth example, and the results are shown in Table 22.
[0231]
[Table 22]

[0232]
(3) Evaluation results
In the composite heat transfer tube of Example 28 of the ninth example, it was observed that a gap was formed at a position corresponding to the groove bottom. In the composite heat transfer tube of Example 34 having the same value of t / T as that of Example 28, the portion where the gap existed was filled with the resin, and the large-diameter tube and the small-diameter tube were directly or in close contact with the resin. ing. For this reason, the heat transfer performance was excellent. In addition, the bending workability was good even when the resin was present.
[0233]
The composite heat transfer tube of Example 30 had fine and small gaps. Then, in the composite heat transfer tube of Example 35 having the same value of t / T as that of Example 30, it was confirmed that the resin was also present in the minute gap portion, and the heat transfer performance was excellent. . Further, as in Example 34, the bending workability was good even when the resin was present.
[0234]
From these results, the presence of the resin between the large-diameter pipe and the small-diameter pipe eliminates the air layer that becomes the thermal resistance and reduces the thermal resistance, resulting in excellent heat transfer performance. It was found that there was no adverse effect on bending workability.
[0235]
(Eleventh embodiment) Embodiments 36 to 39
(1) Preparation of composite heat transfer tube
In the following procedure, as shown in Table 24, t / T is changed in four steps, and four small-diameter pipes are fitted at positions 60 ° apart in the pipe circumferential direction in a cross section orthogonal to the pipe axis of the large-diameter pipe. Four composite heat transfer tubes (Examples 36 to 39) were manufactured.
[0236]
(1-1) Groove formation of large diameter pipe
Table 23 was used for the large diameter pipe. As the material of the large-diameter tube, phosphorous deoxidized copper of alloy number C1201 specified in JIS H3300 was used. The pins shown in Table 6 were used for forming the grooves. 8A, the position of the lower pin 10 is kept as it is, and the upper pins 10, 10 and 10 are moved from the lower pin 10 in the circumferential direction of the large diameter pipe 2 by 60 in FIG. Those arranged at positions separated by ° were used. The other points were the same as in the first embodiment.
[0237]
(1-2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. After annealing, the large-diameter pipe softens and has a tensile strength of 245 to 250 N / mm. ² , 0.2% proof stress is 79-81N / mm ² The elongation was 51 to 53%, and the average crystal grain size (section parallel to the tube axis) was 21 to 23 μm.
[0238]
(1-3) Fitting of small diameter pipe
Table 23 was used for the small diameter pipe. As the material of the small-diameter tube, phosphorous deoxidized copper of alloy number C1220 specified in JIS H3300 was used. Four small-diameter pipes were lightly fitted into four grooves formed in the large-diameter pipe, respectively, and were passed through a rolling roll so that the four small-diameter pipes hit the upper roll. As a result, a composite heat transfer tube in which four small-diameter tubes were fitted at positions separated by 60 ° in the circumferential direction of the large-diameter tube in a section orthogonal to the tube axis was produced.
[0239]
(2) Evaluation items
For one of the four composite heat transfer tubes prepared above, a groove having a length of 8000 mm was cut into 800 mm pieces to prepare 10 samples, and t / T, heat transfer performance, and bending workability were investigated. . The pressure resistance was investigated using the remaining three pieces.
(2-1) t / T
As shown in FIG. 6, t is the groove bottom portions 4b, 4b, 4b, 4b of the four grooves 4, 4, 4, 4 fitted with the four small-diameter tubes 3, 3, 3, 3. Are the average values of the thicknesses t1, t2, t3, and t4 of FIG. In addition, T is a thickness T1 at a predetermined position of the large-diameter pipe 2 that is not fitted with each small-diameter pipe 3 shown in FIG. Of the groove having a length of 8000 mm, samples having a thickness of about 10 mm were collected from three places of 800 mm and 4000 mm from both ends, and a tube axis orthogonal cross section was observed with an optical microscope, and the thicknesses t1, t2, t3, t4 and T1 were measured, and t / T was calculated from the average value thereof.
[0240]
(2-2) Heat transfer performance
Same as the fourth embodiment. Table 24 shows the results.
[0241]
(2-3) Bendability
Same as the fourth embodiment. Table 24 shows the results.
[0242]
(2-4) Compressive strength
Same as the method of the first embodiment. Table 24 shows the results.
[0243]
[Table 23]

[0244]
[Table 24]

[0245]
(3) Evaluation results
As shown in Table 24, in Example 36, the t / T was smaller than the other samples, and the groove formed in the large-diameter pipe became deeper. Was good. Then, a gap was formed at a position corresponding to the groove bottom, but the gap was not large and the heat transfer performance was good. In addition, the thickness of the large-diameter pipe at the groove bottom is reduced, so that the pressure resistance is lower than that of other samples.
[0246]
Example 37 and Example 38 were excellent in heat transfer performance, bending workability, and pressure resistance.
[0247]
In Example 39, the t / T was larger than the other samples, and the groove formed in the large-diameter pipe became shallower, so that the contact length between the large-diameter pipe and the small-diameter pipe in the groove was shorter, and Although the state of adhesion was good, gaps were formed in other parts. The gap was not large, and the heat transfer performance was good. In Example 39, although the fitting force was small, even when the small-diameter pipe was bent so as to come to the inner side surface of the bend in the bending cross section, none of the small-diameter pipes came off the composite heat transfer pipe.
[0248]
(Twelfth embodiment) Embodiment 40
(1) Preparation of composite heat transfer tube
In the following procedure, four small-diameter pipes were fitted at 90 ° apart in the pipe circumferential direction of the large-diameter pipe made of a copper alloy in the pipe circumferential direction (positions at equal intervals in the pipe-axis orthogonal cross section). Four composite heat transfer tubes (Example 40) were produced.
[0249]
(1-1) Groove formation of large diameter pipe
Same as the ninth embodiment. However, the large diameter pipe used was that of Table 25, and the material used was a copper alloy of 0.65 mass% Sn, 0.027 mass% P, 0.35 mass% Zn, and the balance Cu.
[0250]
(1-2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. After annealing, the large-diameter pipe softens and has a tensile strength of 311 N / mm. ² , 0.2% proof stress is 113N / mm ² The elongation was 45% and the average crystal grain size (section parallel to the tube axis) was 15 μm.
[0251]
(1-3) Fitting of small diameter pipe
The small diameter pipes shown in Table 20 are used, and the fitting method is the same as in the ninth embodiment.
[0252]
(2) Evaluation items
Same as the ninth embodiment. The results are shown in Table 26.
(3) Evaluation results
As shown in Table 26, the composite heat transfer tube of Example 40 was excellent in both heat transfer performance and bending workability. Further, since a high-strength alloy tube was used for the large-diameter tube, the pressure resistance was significantly improved as compared with the composite heat transfer tube of Example 31 having substantially the same t / T.
[0253]
[Table 25]

[0254]
[Table 26]

[0255]
(Thirteenth embodiment) Embodiment 41
(1) Preparation of composite heat transfer tube
A composite heat transfer tube (Example 41) in which four small-diameter tubes are fitted at equal intervals in the circumferential direction of the large-diameter tube using an inner grooved tube as the large-diameter tube by the following procedure. This was produced.
[0256]
(1-1) Groove formation of large diameter pipe
Same as the ninth embodiment. However, the large-diameter pipe used in Table 27 was used, and the material used was phosphorous deoxidized copper of alloy number C1220 specified in JIS H3300. The inner surface used had a lead angle of 35 °, a number of grooves of 55, a groove depth of 0.23 mm, and a peak angle of 25 °.
[0257]
(2) Annealing of large-diameter pipe with groove formed
Same as the ninth embodiment. After annealing, the large-diameter pipe softens and has a tensile strength of 220 N / mm ² , 0.2% proof stress is 69N / mm ² The elongation was 50% and the average crystal grain size (section parallel to the tube axis) was 18 μm.
[0258]
(1-3) Fitting of small diameter pipe
The small diameter pipes shown in Table 20 are used, and the fitting method is the same as in the ninth embodiment.
(2) Evaluation items
Same as the ninth embodiment. The results are shown in Table 28.
[0259]
[Table 27]

[0260]
[Table 28]

[0261]
(3) Evaluation results
As shown in Table 28, Example 41 was excellent in heat transfer performance, bending workability, and pressure resistance.
[0262]
(Fourteenth Embodiment) Examples 42 to 51, Comparative Example 3, and Comparative Example 4
(1) Preparation of composite heat transfer tube
A composite heat transfer tube (Example 42 to Example 51) in which four small-diameter tubes having a specific 0.2% proof stress are fitted to a large-diameter tube having a specific 0.2% proof stress by the following procedure. Produced. Further, composite heat transfer tubes (Comparative Examples 3 and 4) using large-diameter tubes that were not subjected to annealing were also manufactured.
[0263]
(1-1) Groove formation of large diameter pipe
Same as the ninth embodiment. However, the large-diameter pipe used in Table 29 was used, and the material used was phosphorus-deoxidized copper of alloy number C1220 specified in JIS H3300 and had a total length of 5200 mm. Further, the pins used in Table 30 were used. D6-No. In D9, the measurement was performed four times (5000 mm × 4). D10 alone was performed 6 times (5000 mm × 6), and a groove was formed in a portion excluding the tube end of 100 mm. Then, in Table 29, No. Grooves were formed in four D8 large-diameter tubes and two in other large-diameter tubes. Table 31 shows the results of the groove formation.
[0264]
(1-2) Annealing of large-diameter pipe with groove formed
Two large-diameter pipes (No. D6 to No. D10 in Table 29) each having a groove were degreased and annealed in a non-oxidizing atmosphere using a roller hearth furnace. The large-diameter pipe after annealing softens and has a tensile strength of 210 to 243 N / mm. ² , 0.2% proof stress 66-83N / mm ² The elongation was 49 to 51% and the average crystal grain size (section parallel to the tube axis) was 20 to 30 μm. Then, in Table 29, No. The other two pieces of D8 were not annealed.
[0265]
(1-3) Fitting of small diameter pipe
Two types (No. S1 and S2) shown in Table 18 were used for the small diameter pipe. Then, the annealed No. D6-No. No. D10 having a large diameter tube and No. Four small-diameter pipes of two types (Nos. S1 and S2) are each lightly fitted into the four grooves formed in the large-diameter pipe of D8, and are passed through rolling rolls as in the ninth embodiment. As a result, a composite heat transfer tube in which four small-diameter pipes were fitted at equally spaced positions in a cross section orthogonal to the pipe axis of the large-diameter pipe was manufactured.
[0266]
(3) Evaluation items
Same as the ninth embodiment. However, excluding bending workability and pressure strength. The results are shown in Table 32.
[0267]
[Table 29]

[0268]
[Table 30]

[0269]
[Table 31]

[0270]
[Table 32]

[0271]
(4) Evaluation results
As shown in Table 32, in Example 42, since the 0.2% proof stress of the large-diameter pipe was small, the portion other than the pin hit when forming the groove portion was easily deformed, and the width was wide (a shape close to a V-shape). Was formed. However, when the small-diameter tube was fitted, the gap generated in the portion other than the projection of the large-diameter tube was not large, and the heat transfer performance was good. Further, in Example 43 using a soft small-diameter tube (S2), the small-diameter tube was deformed by rolling, but the generated gap was not large and the heat transfer performance was good.
[0272]
In Example 44, Example 46, and Example 48, since hard materials (S1) were fitted as small-diameter tubes, there was little generation of gaps, and the heat transfer performance was excellent. In Example 45, Example 47, and Example 49, the small-diameter pipes were deformed by rolling because the soft ones (S2) were fitted. However, the generated gap was not large and the transmission was not large. Thermal performance was good.
[0273]
In Example 50 and Example 51, the large-diameter pipe was hard, so it took time to form the groove. However, similarly to Examples 44 to 49, the generated gap was not large, and the heat transfer performance was good. there were.
[0274]
In Comparative Examples 3 and 4, since the large-diameter pipe was not annealed, the small-diameter pipe was fitted into the large-diameter pipe in a hard state, and the small-diameter pipe was hard to enter the groove of the large-diameter pipe. However, the projection of the large-diameter pipe over the small-diameter pipe was not sufficient. Therefore, many large gaps were formed at the bottom of the groove, and the heat transfer performance was poor.
[0275]
From the above, it is assumed that the large-diameter pipe before forming the groove on the outer surface of the pipe has a 0.2% proof stress σ in the pipe axis direction. _0.2 Is 200 to 370 N / mm ² And a 0.2% proof stress σ as a small-diameter tube. _0.2 Is 200 N / mm ² It can be seen that it is preferable to use the above.
[0276]
(Fifteenth embodiment) Embodiments 52 to 54
(1) Preparation of composite heat transfer tube
According to the following procedure, two composite heat transfer tubes fitted to each other while changing the contact length between the small-diameter tube and the large-diameter tube in the cross section orthogonal to the tube axis were produced, and Examples 52 to 54 were respectively obtained.
[0277]
(1-1) Groove formation of large diameter pipe
The used large-diameter tube and pins are the same as in the ninth embodiment. The depth of the groove was changed to three types by changing the pressing load and the number of movements of the pin, and the shallowest groove was used in Example 52 and the deepest groove was used in Example 54.
[0278]
(1-2) Annealing of large-diameter pipe with groove formed
This is the same as the ninth embodiment.
[0279]
(1-3) Fitting of small diameter pipe
The used small diameter pipe is the same as that of the ninth embodiment. Then, a small-diameter tube was fitted in the same manner as in the ninth embodiment.
[0280]
(2) Evaluation items
The contact length of the small diameter tube at the fitting portion was measured by the method described in the embodiment of the present invention. The heat transfer property and bending workability were evaluated in the same manner as in the ninth example, and the results are shown in Table 33.
[0281]
[Table 33]

[0282]
(3) Evaluation results
As shown in Table 33, the contact length of the small-diameter tube was 52% for the composite heat transfer tube of Example 52, 55% for the composite heat transfer tube of Example 53, and 80% for the composite heat transfer tube of Example 54. In each of the composite heat transfer tubes of Examples 52 to 54, the small-diameter tube was correctly fitted to the large-diameter tube, and the heat transfer performance was excellent. In the bending workability, in Example 52 in which the contact length of the small-diameter pipe was less than 55%, two of the five small-diameter pipes came off, but the contact length of the small-diameter pipe was 55% or more. The composite heat transfer tubes of Example 53 and Example 53 had good results. This shows that the contact length of the small-diameter pipe is preferably 55% or more especially when bending is performed.
[0283]
Further, a tube expansion test was performed using the remaining one composite heat transfer tube of each example. When a tube expansion plug was inserted into both ends of the composite heat transfer tube of Example 52 to expand the inner diameter to 12 mm, the tube could be expanded without cracks. The composite heat transfer tubes of Examples 52 and 53 were annealed in a non-oxidizing atmosphere using a roller hearth furnace. When expanded pipes were inserted into both ends of the annealed composite heat transfer tube so as to have an inner diameter of 12 mm, it was possible to expand the pipe without cracks.
[0284]
(Sixteenth Embodiment) Embodiments 55 to 62
(1) Preparation of composite heat transfer tube
In the following procedure, as shown in Table 35, t / T was changed in five steps, and four small-diameter pipes were fitted at 90 ° apart in a cross section orthogonal to the pipe axis of the large-diameter pipe. As shown, four composite heat transfer tubes (Example 55 to Example 62) each having a spirally wound portion were produced.
[0285]
(1-1) Groove formation of large diameter pipe
The procedure for forming the pins and grooves used was the same as in the ninth embodiment. The large-diameter tube used in Table 34 was used.
[0286]
(1-2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. The large-diameter pipe after annealing softens and has a tensile strength of 231 to 238 N / mm. ² , 0.2% proof stress 71-75 N / mm ² The elongation was 50 to 52%, and the average crystal grain size was 25 μm (section parallel to the tube axis).
[0287]
(1-3) Fitting of small diameter pipe
Table 34 is used for four small diameter pipes. The fitting method was the same as in the ninth embodiment.
[0288]
(1-4) Annealing of a large-diameter pipe fitted with a small-diameter pipe
In Example 58 and Example 59, after fitting four small diameter tubes, annealing was performed under the same conditions as in (1-2). The large diameter pipe has a tensile strength of 228N / mm by annealing. ² , 0.2% proof stress 70N / mm ² , Elongation 51%, small diameter pipe has tensile strength 260N / mm ² , 0.2% proof stress 143N / mm ² , And softened to an elongation of 45%. In each case, the average crystal grain size (cutting method) observed in a cross section parallel to the tube axis was about 25 μm.
[0289]
(1-5) Production of spiral composite heat transfer tube
As shown in FIG. 13 and FIG. 14 (a), the four samples manufactured in the above (1-3) and (1-4) were used to fit four small-diameter pipes into a large-diameter pipe. Was spirally wound 20 times, and four spiral composite heat transfer tubes each having a minimum inner diameter ID of 150 mm and an average pitch p of about 13.0 mm were produced. In addition, about Example 56, Example 58, and Example 60, annealing was performed on the same conditions as (1-2).
[0290]
(2) Evaluation items
One of the four spiral composite heat transfer tubes prepared above was examined for t / T and heat transfer performance, and for the remaining three tubes, detachment and pressure resistance of the small diameter tube were investigated.
(2-1) t / T
Test pieces were cut out from the end, the center, and the lower end of the spirally wound composite heat transfer tube, and evaluated in the same manner as in the ninth embodiment. The results are shown in Table 35.
[0291]
(2-2) Heat transfer performance
Evaluation was performed in the same manner as in the ninth example, and the results are shown in Table 35.
[0292]
(2-3) Separation of small diameter pipe
The external appearance of the helical composite heat transfer tube was visually observed, and it was observed whether there was a portion where the small-diameter tube was floating or a portion where the small-diameter tube was detached from the large-diameter tube (n = 3).
[0293]
(2-4) Compressive strength
After the evaluation of the above (2-3), the large-diameter pipe was filled with water and gradually pressurized with a hand pump, and the pressure at which the small-diameter pipe began to separate from the large-diameter pipe was read with a Bourdon pipe gauge. Evaluation was performed with an average value of n = 3.
[0294]
[Table 34]

[0295]
[Table 35]

[0296]
(3) Evaluation results
In Example 55, the t / T was smaller than that of the other samples, and the groove formed in the large-diameter pipe was deeper. Was good. Then, it was observed that a rather large gap was formed at a position corresponding to the groove bottom, but the heat transfer performance was good. In addition, since the large diameter pipe had a large margin, the small diameter pipe did not separate even when it was formed into a coil. Since the thickness of the large-diameter tube in the fitting portion was reduced, the pressure resistance was lower by about 10 to 30% than in the other samples.
[0297]
In Examples 56 to 61, the heat transfer performance was good because the small-diameter pipe was firmly fitted to the large-diameter pipe with and without annealing, and in all cases, detachment of the small-diameter pipe occurred. Did not. Also, the pressure resistance was good.
[0298]
In the samples subjected to annealing 2 of Examples 56, 58 and 60, the residual stress was removed by annealing after winding, and the large-diameter pipe and the small-diameter pipe were in close contact with each other. It was higher than the sample.
[0299]
In Example 62, the t / T was larger than the other samples, and the groove formed in the large-diameter pipe became shallower. It became shorter, and the close contact condition of the groove edge of the large-diameter pipe was good, but in other parts, a part with a large gap was observed. However, the heat transfer performance was good. In addition, since the fitting force of the large-diameter tube to the small-diameter tube is small, the small-diameter tube is slightly detached when spirally wound, and the pressure resistance tends to decrease.
[0300]
From these results, it can be seen that t / T is preferably in the range of 0.3 to 0.7 in order to satisfy all of the heat transfer performance, bending workability, and pressure resistance. In addition, it has been found that annealing after the spiral winding is effective in detaching the small-diameter tube by the spiral winding, and increasing the heat transfer performance and the pressure resistance.
[0301]
(Seventeenth embodiment) Embodiment 63
(1) Preparation of composite heat transfer tube
In the following procedure, a spiral composite heat transfer tube (Example 63) in which four small-diameter tubes are fitted at positions 60 ° apart in a cross section perpendicular to the tube axis of a large-diameter tube and a spiral winding portion is formed. ) Was prepared.
[0302]
(1-1) Groove formation of large diameter pipe
The thing of Table 36 was used for the large diameter pipe. Also, the pins shown in Table 37 were used to form the grooves, the upper pins were left in the same position, and the lower pins were placed 60 ° away from the upper pins in the circumferential direction of the large diameter pipe. Was used. Other points are the same as the sixteenth embodiment.
[0303]
[Table 36]

[0304]
[Table 37]

[0305]
(1-2) Annealing of large-diameter pipe with groove formed
The large-diameter pipe in which the groove was formed was degreased, and the large-diameter pipe was annealed in a non-oxidizing atmosphere using a roller hearth furnace. The large-diameter pipe after annealing softens and has a tensile strength of 250 N / mm ² , 0.2% proof stress 81N / mm ² , Elongation 53%, and average crystal grain size 23 μm (section parallel to the tube axis).
[0306]
(1-3) Fitting of small diameter pipe
The four small diameter pipes were passed through a rolling roll so as to hit the upper roll. Other points are the same as the sixteenth embodiment.
[0307]
(1-4) Annealing of a large-diameter pipe fitted with a small-diameter pipe
No annealing was performed.
[0308]
(1-5) Production of spiral composite heat transfer tube
Same as the sixteenth embodiment. Annealing after winding was also performed. Then, the produced spiral composite heat transfer tube was evaluated in the same manner as in the sixteenth embodiment. The strength was also good.
[0309]
(Eighteenth Embodiment) Embodiment 64
(1) Preparation of composite heat transfer tube
A composite heat transfer tube in which two spiral winding portions are formed as shown in FIG. 15 in which a small-diameter tube is fitted at a position 90 ° away from the cross section of the large-diameter tube orthogonal to the tube axis by the following procedure. Example 64) was produced.
[0310]
(1-1) Groove formation of large diameter pipe
This is the same as the sixteenth embodiment.
[0311]
(1-2) Annealing of large-diameter pipe with groove formed
This is the same as the sixteenth embodiment.
[0312]
(1-3) Fitting of small diameter pipe
This is the same as the sixteenth embodiment.
[0313]
(1-4) Annealing of a large-diameter pipe fitted with a small-diameter pipe
No annealing was performed.
[0314]
(1-5) Preparation of spiral composite heat transfer tube
As shown in FIGS. 15 and 16 (a), the sample manufactured in the above (1-3) was spirally wound over the entire length of the portion where four small diameter tubes were fitted to the large diameter tube. Is wound 7 times in the direction in which the diameter is reduced, and subsequently, it is wound 7 times in the direction in which the winding diameter is increased. The minimum inner diameter ID of the two winding portions 61k and 61k is 200 mm, and the maximum outer diameter OD is 400 mm. A spiral composite heat transfer tube having an average pitch p of about 13.5 mm was produced. After the winding, annealing was performed under the same conditions as in the sixteenth example.
[0315]
(2) Evaluation items (heat transfer performance)
Water at a flow rate of 1.16 kg / min is passed through the large-diameter tube of the prepared spiral composite heat transfer tube, and CO of 11.5 MPa is passed through four small-diameter tubes. ₂ Shed. This spiral heat transfer tube was operated for 1000 hours, and the heat transfer performance was confirmed by observing a change in the outlet temperature (large-diameter tube) with respect to the inlet temperature (large-diameter tube) during operation.
[0316]
(3) Evaluation results
The outlet temperature to the inlet temperature of the large diameter pipe was always stable.
[0317]
(19th embodiment) Embodiment 65
(1) Preparation of composite heat transfer tube
In the following procedure, a composite heat transfer tube in which four small-diameter tubes are fitted at 90 ° apart in a cross section orthogonal to the tube axis of a large-diameter tube and in which one spiral winding portion is formed (Example 65) ) Was prepared.
[0318]
(1-1) Groove formation of large diameter pipe
This is the same as the eighteenth embodiment. The length of the large-diameter pipe and the small-diameter pipe is 5000 mm.
[0319]
(1-2) Annealing of large-diameter pipe with groove formed
This is the same as the eighteenth embodiment.
[0320]
(1-3) Fitting of small diameter pipe
This is the same as the eighteenth embodiment.
[0321]
(1-4) Annealing of a large-diameter pipe fitted with a small-diameter pipe
No annealing was performed.
[0322]
(1-5) Preparation of spiral composite heat transfer tube
As in the eighteenth embodiment, the entire length of the portion where the four small-diameter pipes are fitted to the large-diameter pipe is spirally wound seven times in the direction in which the winding diameter is reduced. A spiral composite heat transfer tube having an inner diameter of 200 mm, a maximum outer diameter of 400 mm, and an average pitch p of about 13.5 mm was produced. After the winding, annealing was performed under the same conditions as in the eighteenth example.
[0323]
(2) Evaluation items (heat transfer performance)
This is the same as the eighteenth embodiment.
[0324]
(3) Evaluation results
The outlet temperature to the inlet temperature of the large diameter pipe was always stable.
[0325]
(Twentieth embodiment) Embodiment 66
(1) Preparation of composite heat transfer tube
In the following procedure, two spiral composite heat transfer tubes similar to those of the nineteenth example were produced, and a composite heat transfer tube (Example 66) in which each was combined was produced.
[0326]
(1-1) Groove formation of large diameter pipe
This is the same as the nineteenth embodiment.
[0327]
(1-2) Annealing of large-diameter pipe with groove formed
This is the same as the nineteenth embodiment.
[0328]
(1-3) Fitting of small diameter pipe
This is the same as the nineteenth embodiment.
[0329]
(1-4) Annealing of a large-diameter pipe fitted with a small-diameter pipe
No annealing was performed.
[0330]
(1-5) Preparation of spiral composite heat transfer tube
Same as the nineteenth embodiment. One end of the two spiral composite heat transfer tubes thus produced was expanded, and the respective tube ends were joined by brazing.
[0331]
(2) Evaluation items (heat transfer performance)
This is the same as the nineteenth embodiment.
[0332]
(3) Evaluation results
The outlet temperature to the inlet temperature of the large diameter pipe was always stable. Also, no leakage from the brazing portion was observed.
[0333]
【The invention's effect】
With the configuration as described above, the composite heat transfer tube according to the present invention has the following excellent effects.
[0334]
In the composite heat transfer tube, since the surface of the groove of the large-diameter pipe adjacent to the small-diameter pipe has an arc equal to the arc of the small-diameter pipe, the small-diameter pipe adheres closely to the surface of the groove, and the large-diameter pipe and the small-diameter pipe As the area of the contact portion (heat transfer area) increases, the large-diameter pipe and the small-diameter pipe are firmly fitted, and the small-diameter pipe can be prevented from coming off (falling out) from the groove. Therefore, the composite heat transfer tube can be appropriately manufactured to have a desired heat transfer performance, and is excellent in productivity. Further, since the composite heat transfer tube has good heat transfer performance, sufficient pressure resistance, and can be manufactured compactly, a device such as a refrigerator using the composite heat transfer tube can be downsized.
[0335]
In addition, the composite heat transfer tube further improves the heat transfer performance at the fitting portion by setting the outer diameters at both ends of the large-diameter tube and the small-diameter tube to a predetermined range, is reduced in size, and is incorporated in the heat exchanger. At this time, it is easy to join with another pipe, which is convenient.
[0336]
Further, in the composite heat transfer tube, when the large-diameter tube has a thickness t at a groove bottom portion of the groove portion fitted with the small-diameter tube and a thickness T at a portion not fitted with the small-diameter tube, t By using a composite heat transfer tube having a value of / T of 0.3 to 0.7, it becomes easy to fit a small-diameter tube to a large-diameter tube, and a gap is formed between the large-diameter tube and the small-diameter tube. In addition, the groove bottom portion has a stress that can oppose the internal pressure of the large-diameter pipe, and the fitted small-diameter pipe is prevented from being pushed out of the large-diameter pipe. Further, the heat transfer performance between the large-diameter pipe and the small-diameter pipe is improved, the bending workability can be improved, and the arc of the surface of the groove of the large-diameter pipe is made equal to the arc of the small-diameter pipe. Can be formed.
[0337]
In addition, the composite heat transfer tube is designed such that the apparent contact length between the small-diameter tube and the large-diameter tube in the cross section orthogonal to the tube axis of the composite heat transfer tube is equal to or longer than a predetermined length, so that the heat transfer between the large-diameter tube and the small-diameter tube is performed. The area is further increased, and the fitting force of the small diameter tube to the large diameter tube is further increased.
[0338]
In addition, the heat transfer efficiency between the large-diameter pipe and the small-diameter pipe is improved by arranging the small-diameter pipes at equidistant positions in a cross section orthogonal to the pipe axis of the large-diameter pipe. The groove for accommodating the small-diameter pipe is formed, and the workability of rolling-fitting the small-diameter pipe into the groove is good and the productivity is excellent.
[0339]
In addition, the heat transfer area of the large-diameter tube is further increased by forming a groove or a spiral groove parallel to the tube axis direction on the inner surface of the large-diameter tube. Thermal performance is further improved.
[0340]
Further, the composite heat transfer tube, by fitting the large-diameter tube and the small-diameter tube via the resin, the resin is also filled in the fine gap formed in the contact surface of the large-diameter tube and the small-diameter tube, The air with low thermal conductivity is eliminated from the contact surface, the degree of adhesion between the large-diameter tube and the small-diameter tube is further increased, the heat transfer area between the large-diameter tube and the small-diameter tube is further increased, and the small-diameter tube is connected to the large-diameter tube. The fitting force further increases.
[0341]
In addition, the composite heat transfer tube has a large-diameter tube and / or a small-diameter tube made of oxygen-free copper or phosphorous deoxidized copper, so that the large-diameter tube and / or the small-diameter tube have thermal conductivity, corrosion resistance, and plastic workability. (Fitting, bending, etc.), the pressure resistance is improved, and the solderability when incorporated into a heat exchanger is improved.
[0342]
Further, by forming the spirally or spirally wound portion of the composite heat transfer tube, the heat transfer area of the composite heat transfer tube increases and the composite heat transfer tube can be made compact. This facilitates installation in the heat exchanger and allows stable installation. Further, by making the outer shape of the large-diameter pipe in a cross section orthogonal to the pipe axis into a flat circle, the composite heat transfer pipe becomes more compact.
[0343]
Further, the method for manufacturing a composite heat transfer tube includes a groove forming step, an annealing step, a rolling fitting step, or further includes a resin applying step and a resin curing step, or further includes a winding step, a pipe expanding step In addition, since at least one of the annealing step and the annealing step is performed, it is possible to appropriately manufacture a compact composite heat transfer tube that has sufficient heat-resistant performance and sufficient pressure resistance.
[Brief description of the drawings]
FIG. 1A is a side view of a composite heat transfer tube including three small-diameter tubes according to the present invention, and FIG. 1B is a partially cut perspective view showing an end of a groove.
FIG. 2 is a cross-sectional view of the composite heat transfer tube according to the present invention taken along line XX of FIG.
FIG. 3 is a cross-sectional view of another embodiment of the composite heat transfer tube of FIG. 2 according to the present invention.
FIG. 4 is a cross-sectional view of another embodiment of the composite heat transfer tube of FIG. 2 according to the present invention.
FIG. 5 is a cross-sectional view of a composite heat transfer tube including four small-diameter tubes according to the present invention.
FIG. 6 is a cross-sectional view of another embodiment of the composite heat transfer tube of FIG. 5 according to the present invention.
FIG. 7 is a tube axis parallel cross-sectional view schematically illustrating a groove forming step of forming grooves at four locations of a large-diameter tube of the composite heat transfer tube according to the present invention.
FIGS. 8A and 8B are cross-sectional views schematically showing a groove forming step of forming a groove in a large-diameter tube of the composite heat transfer tube according to the present invention, wherein FIG. This is the case where there are three grooves.
FIG. 9 is a tube axis parallel sectional view schematically showing a rolling fitting step of fitting four small diameter pipes to a large diameter pipe of the composite heat transfer tube according to the present invention.
FIG. 10 is a sectional view orthogonal to the tube axis schematically showing a rolling fitting step of fitting a small-diameter tube to a large-diameter tube of the composite heat transfer tube according to the present invention, where (a) shows a case where there are four small-diameter tubes; (B) is a case where there are three small diameter tubes.
11A is a partially enlarged cross-sectional view of a groove before fitting of FIG. 10 according to the present invention, FIG. 11B is a partially enlarged cross-sectional view of a groove after fitting, and FIG. It is a partial expanded sectional view of the embodiment.
FIG. 12 is an explanatory view schematically showing a configuration of a heat exchanger using the composite heat transfer tube according to the present invention.
FIG. 13 is a perspective view of a composite heat transfer tube having a spirally wound portion according to the present invention.
14A is a cross-sectional view taken along line CC of FIG. 7, and FIGS. 14B and 14C are partial cross-sectional views showing another embodiment of FIG.
FIG. 15 is a perspective view of a composite heat transfer tube having a spirally wound portion according to the present invention.
16A is a cross-sectional view taken along the line DD of FIG. 9, and FIG. 16B is a partial cross-sectional view showing another embodiment of FIG.
FIG. 17 is a cross-sectional view of a conventional composite heat transfer tube.
18 (a) and (b) are cross-sectional views of another conventional composite heat transfer tube.
FIG. 19 is a perspective view of another conventional composite heat transfer tube.
[Explanation of symbols]
1, 31, 41, 51, 61, 71 composite heat transfer tubes
2, 52, 72 Large diameter pipe
2a Both ends
3, 53, 73 Small diameter pipe
3a Both ends
3A arc
4 groove
4a Projection
4b Groove bottom
4A surface
5 resin
31k, 41k, 51k, 61k, 71k winding part
61i, 71i transition section
10 pins
11 Groove processing part
11a Tip of grooved part
12 gripper
13 Joint
14 Shoulder
15 sleeve
16 Rolling roll
20 heat exchanger
21 Compressor
22 radiator
23 Cooler
A Part other than compounding section B
B Composite section
θ angle
d outer diameter
ID Minimum inner diameter
OD maximum outer diameter
H height
a Tube outer diameter
p interval

Claims (17)

A large-diameter pipe having three or four grooves formed in at least a part of the outer surface excluding both ends in parallel with the pipe axis direction, and a diameter smaller than the diameter of the large-diameter pipe; A composite heat transfer tube including three or four small-diameter tubes each fitted in the groove portion,
The composite heat transfer tube according to claim 1, wherein a surface of the groove adjacent to the small-diameter pipe has an arc equal to an arc of the small-diameter pipe in contact with the surface. The outer diameter at both ends of the large-diameter pipe is the same as or larger than the outer diameter of the large-diameter pipe in the portion where the small-diameter pipe is fitted, and the outer diameters at both ends of the small-diameter pipe are other. The composite heat transfer tube according to claim 1, wherein the outer diameter of the small diameter tube in the portion is equal to or larger than the outer diameter of the small diameter tube. The value of t / T is such that the large-diameter pipe has a thickness t at a groove bottom portion of a groove portion fitted with the small-diameter pipe and a thickness T at a portion not fitted with the small-diameter pipe. The composite heat transfer tube according to claim 1 or 2, wherein the value is 0.3 to 0.7. The arc of the surface of the groove adjacent to the small-diameter pipe is the apparent contact length between the small-diameter pipe and the large-diameter pipe in a cross section orthogonal to the pipe axis of the composite heat transfer pipe, and is the entire circumference of the small-diameter pipe. The composite heat transfer tube according to any one of claims 1 to 3, wherein the composite heat transfer tube is 55% or more of the following. The three or four small-diameter pipes are fitted into three or four grooves arranged at equal intervals on the circumference of the large-diameter pipe in a cross section orthogonal to the pipe axis of the large-diameter pipe. The composite heat transfer tube according to any one of claims 1 to 4, wherein the composite heat transfer tube is formed. The composite heat transfer tube according to any one of claims 1 to 5, wherein a groove or a spiral groove parallel to the tube axis direction is formed on an inner surface of the large-diameter tube. The three or four small-diameter pipes are fitted with the large-diameter pipe via a resin at least in a part of the surface of the three or four groove parts. The composite heat transfer tube according to claim 6. The composite transmission according to any one of claims 1 to 7, wherein at least one of the large-diameter tube and the small-diameter tube is a copper tube or a copper alloy tube made of oxygen-free copper or phosphorus-deoxidized copper. Heat tubes. The large-diameter pipe in which three or four of the small-diameter pipes are fitted forms a helically wound part that is spirally wound. Composite heat transfer tube. The large-diameter pipe fitted with three or four of the small-diameter pipes forms a spirally wound part that is spirally wound. Composite heat transfer tube. The composite heat transfer tube according to claim 9, wherein an outer shape of the large-diameter pipe in a cross section orthogonal to a pipe axis has a flat circular cross-sectional shape. A method for manufacturing a composite heat transfer tube comprising: a large-diameter pipe, and three or four small-diameter pipes fitted on an outer surface of the large-diameter pipe in parallel with a pipe axis direction of the large-diameter pipe,
A pin is pressed against an outer surface of the large-diameter pipe except for both ends, and the pin is fixed to move the large-diameter pipe in parallel with the pipe axis direction, or the pin is fixed to the large-diameter pipe. A groove portion forming a groove extending in the tube axis direction at three or four locations on the outer surface of the large diameter tube by moving
An annealing step of annealing the large-diameter pipe in which the groove is formed,
Three or four small-diameter pipes are placed in three or four of the grooves, and the small-diameter pipes are rolled by rolling rolls to embed the small-diameter pipes in the grooves, and the annealed large-diameter pipes and the small-diameter pipes are fitted. A method of manufacturing a composite heat transfer tube, comprising: At least one of the large-diameter tube and the small-diameter tube is a copper tube or a copper alloy tube made of oxygen-free copper or phosphorus deoxidized copper,
The large-diameter pipe has a 0.2% proof stress of 200 to 370 N / mm ² in the pipe axis direction before forming the groove on the outer surface thereof,
The small diameter tube, method for producing a composite heat transfer tube according to claim 12, 0.2% proof stress in the tube axis direction is equal to or is 200 N / mm ² or more. After the rolling fitting step, a winding step of winding the large-diameter pipe fitted with the small-diameter pipe with a predetermined radius, an expanding step of expanding a pipe end of the large-diameter pipe and / or the small-diameter pipe, and 14. The method according to claim 12, wherein at least one of the annealing steps is performed. A method for manufacturing a composite heat transfer tube comprising: a large-diameter pipe, and three or four small-diameter pipes fitted on an outer surface of the large-diameter pipe in parallel with a pipe axis direction of the large-diameter pipe,
A pin is pressed against an outer surface of the large-diameter pipe except for both ends, and the pin is fixed to move the large-diameter pipe in parallel with the pipe axis direction, or the pin is fixed to the large-diameter pipe. A groove portion forming a groove extending in the tube axis direction at three or four locations on the outer surface of the large diameter tube by moving
An annealing step of annealing the large-diameter pipe in which the groove is formed,
A resin is applied to at least a part of the surface of the three or four grooves, or at least a part of the outer surface of the three or four small diameter pipes that fits with the annealed large diameter pipe. A resin application step of applying resin to a part,
Three or four small-diameter pipes are placed in three or four of the grooves, and the small-diameter pipes are rolled by rolling rolls to embed the small-diameter pipes in the grooves, and the large-diameter pipes annealed via the resin. Rolling fitting step of fitting the small diameter pipe,
Heating the rolled-fit composite heat transfer tube to a curing temperature of the resin, heating the resin for a predetermined time, and curing the resin. At least one of the large-diameter tube and the small-diameter tube is a copper tube or a copper alloy tube made of oxygen-free copper or phosphorus deoxidized copper,
The large-diameter pipe has a 0.2% proof stress of 200 to 370 N / mm ² in the pipe axis direction before forming the groove on the outer surface thereof,
The small diameter tube, method for producing a composite heat transfer tube according to claim 15, 0.2% proof stress in the tube axis direction is equal to or is 200 N / mm ² or more. After the rolling fitting step, a winding step of winding the large-diameter pipe fitted with the small-diameter pipe with a predetermined radius, an expanding step of expanding a pipe end of the large-diameter pipe and / or the small-diameter pipe, and 17. The method according to claim 15, wherein at least one of the annealing steps is performed.

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